The Polanes' neighbors to the West were tribes of Sorbs and Polabians. The Holy Roman Empire and her duchies had established marches in this region. The Pomeranian tribes dwelled in the North. Polish dukes, at times vassals or allies of the empire, tried to expand their realm into these areas as well as the Germans and the Danes. Lands under Duke Mieszko's rule, including lands kept as vassal of the emperor and as margrave, encompassed Greater Poland, Lesser Poland, Masovia, Silesia and Pomerania. The lands totalled about 250,000 km² in area, with a population of about 1 million.
Mieszko I married Dubrawka, daughter of the Czech duke Boleslav I and was baptised into the Roman branch of Christianity in 966. This event started widespread conversion to Christianity within the Mieszko I realms, and was also a fact of political significance. It marked the beginning of Poland as part of the Christian western world. Moreover he also allied with the Czechs to try to keep the German land conquered or received as lien for themselves. He was christened by a Czech clergyman.
In 967 the Polish ruler defeated German Count Wichman and his allies. In 972 at the Battle of Cedynia, Mieszko defeated Hodo of the Eastern March, which enabled him to take over areas in Pomerania, as margrave of the emperor. Mieszko I died in 992 and left his son and successor Bolesław I the Brave a strong and thriving dukedom.
Boleslaw continued the work of his father. He was able to preserve the unity of the country by expelling Ode (Mieszko I's second wife) and her sons. At the Congress of Gniezno (1000) he was able to persuade Emperor Otto III to give his permission to create the first Polish archbishopric.
After the untimely death of Otto III in 1002 at the age of 22, Boleslaw I conquered the imperial March of Meissen (Polish Miśnia) and also Lausitz (Latin Lusatia, Polish Łużyce), thereby trying to wrest imperial territory for himself during the disputes over the throne — he and his father had both earlier backed Duke Henry II ("the Quarrelsome") of Bavaria against Otto, and he accepted the accession of Duke Henry's son as the Emperor Henry II. Boleslaw conquered and made himself duke of Bohemia in 1003, but lost the territory the following year. He defeated the Rus' and stormed Kyiv in 1018.
He was forced to give a pledge of allegiance by Emperor Henry II again, for the lands he held in fief. Henry died in 1024. A year later in 1025, shortly before his death, Boleslaw was crowned king. His coronation marked the full political and territorial independence of the Polish State.
Mieszko's son and successor Boleslaw I (992–1025), known as the Brave, built on his father's achievements and became the most successful Polish monarch of the early medieval era. Boleslaw continued the policy of appeasing the Germans while taking advantage of their political situation to gain territory wherever possible. Frustrated in his efforts to form an equal partnership with the Holy Roman Empire, Boleslaw gained some non-Polish territory in a series of wars against his imperial overlord in 1003 and 1004. The Polish conqueror then turned eastward, extending the boundaries of his realm into present-day Ukraine. Shortly before his death in 1025, Boleslaw won international recognition as the first king of a fully sovereign Poland.
Mieszko II was crowned in 1025 after his father's death. The many landlords, however, feared the single rule of the monarch. This situation led to conflicts in the country, in which Mieszko's brothers turned against him and the Emperor Conrad II's forces attacked the country, seizing Lusatia. Years of chaos and conflict followed, during which Mieszko died (1034) in suspicious circumstances after his forced abdication and a brief restoration.
The reign of Casimir I the Restorer (1037–1058) was a short period of stability. Casimir unified the country, and was succeeded by Boleslaus II, who took advantage of the conflict between emperor Henry IV and Pope Gregory VII and made himself king in 1076. The landlords rebelled yet again and Boleslaus II had to abdicate in 1079. His brother Władysław I Herman took over the throne and also had to abdicate in 1102, giving the power to his sons Zbigniew of Poland and Bolesław III Wrymouth who reigned simultaneously, until Boleslaw had his half-brother banished from the country in 1107 and blinded in 1112.
It was Boleslaw who united the country in 1106 and defended it against the Holy Roman Empire later on. He managed to again conquer all the previously conquered territories, held for a short time, including Pomerania. Before his death in 1138 he split up the power in country between his sons. Following his theory of seniorate, Boleslaw divided the country into five principalities Silesia, Greater Poland, Mazovia, Sandomir and Kraków. The first four provinces were divided among his four sons who became independent rulers. The fifth province, that of Kraków, was to be added to the senior among the Princes who, as the Grand Duke of Kraków, was the representative of the whole of Poland.
No sooner did Boleslaw die than his oldest son, Władysław, conceived the idea of restoring Poland's unity by depriving his brothers of their shares. He met with the determined opposition of the Church and the magnates, who clearly recognized that a centralized power was detrimental to their interests and influence. The Archbishop of Gniezno insulted Wladyslaw and two powerful potentates organized an army against him. A civil war ensued which, despite the help received from outside and the interference of Friedrick Barbarossa, ended in the defeat of the Grand Duke of Kraków 1146. This marks the beginning of the era of disintegration of the young Polish state and the decline of monarchical power in Poland. The principalities of Silesia, Greater Poland and Mazovia had become divided into smaller units, with further sub-divisions and occasional fusions. Separatist interests and jealousies led to almost incessant warfare.
The ruler of Kraków retained the title of Dux Poloniae, the Duke of Poland, but the security of his office depended upon his relations with the aristocracy and clergy. Casimir II of Poland (1177–1194) had been obliged to summon a council of nobles and clergy and to surrender certain of his rights and privileges. He was also compelled to promise to call such councils when important matters of state were to be decided upon. At the Council or Synod of Łęczyca (1180) the Church, under the threat of an interdict, enjoined the Duke from the exercise of his right to the personal property of deceased bishops (Ius Spolii) and to certain levies for his officials and representatives. In return for these concessions or immunities the Council abolished the seniorate and vested in the line of Casimir the Just the perpetual right to the principality of Kraków. Thus the right of seniority in the Piast Dynasty gave way to the law of primogeniture in the line of Casimir the Just. In 1205, Leszek I the White and his brother, Konrad I of Masovia, won a great victory over Roman the Great at the Battle of Zawichost, killing the Ruthenian lord in battle. It was also that year that the Poles first heard of Lithuanians, when the latter invaded Ruthenia.
This right was frequently contested by armed interference. The authority of the Duke of Kraków was not adequately defined by law and was ignored in actual practice. The heads of the smaller principalities were in fact independent rulers, free to establish alliances for defensive and offensive warfare, to make treaties and to maintain independent customs barriers. In other words, Poland of the 13th century was no longer one solid political entity. The sovereignty of the former state became diffused among a number of smaller independent political units, with only the common bonds of language, race, religion and tradition.
The princely power was theoretically unlimited. By the "grace of God" the princes were absolute lords of their dominions. Actually, the exercise of their power depended on the strength or weakness of the barons and clergy and on their own skill in playing off the interests of the one against those of the other. The barons and the clergy became very powerful in the 13th century. Both classes acquired large land holdings with jurisdiction over their subjects. The Church grew constantly stronger on account of its splendid organization, its accumulation of wealth and the moral control it exercised over the people. Then, too, it had become more independent since the adoption of the Gregorian reforms, which deprived the king of the power to appoint bishops. By their presence at the Councils of the Prince, called Colloquia they, in conjunction with the barons, exercised direct control over the affairs of the principality. The Colloquium was called at such times as state business demanded. In addition to the relatives of the prince, the barons and prelates were invited to attend it, and at these gatherings matters of foreign policies, as well as of internal administration, were determined. The granting of franchises, the fixing of taxes and matters of like nature were decided at these meetings, and at times the Colloquium also served as the Prince's Court. The Colloquium was the nucleus of what later developed into the Senate.
Concurrent with the metamorphosis in the structure of the Polish State and sovereignty was an economic and social impoverishment of the country. Harassed by civil strife and foreign invasions, like that of the Mongols in 1241, the small principalities became enfeebled and depopulated. The incomes of the Princes began to decrease materially. This led them to take steps toward encouraging immigration from foreign countries. A great number of German peasants, who, during the interregnum following the death of Frederick II, suffered great oppression at the hands of their lords, were induced to settle in Poland under certain very favorable conditions. German immigration into Poland had started spontaneously at an earlier period, about the end of the 11th century, and was the result of overpopulation in the central provinces of the Empire. Advantage of the existing tendency had already been taken by the Polish Princes in the 12th century for the development of cities and crafts. Now the movement became intensified.
Some studies of the development of the German settlements in Poland indicate that they sprang up along the wide belt which was laid waste by the Mongols in 1241. It was a stretch of land comprising present Galicia and Southern Silesia. Prior to the Mongol invasion these two provinces were thickly settled and highly developed. Through them ran the commercial highways from the East and the Levant to the Baltic and the west of Europe. Kraków and Wrocław were large and prosperous towns. Some historians, mostly those stressing the scale of German settlements, claim that after the Mongol barbarians retired the country was in ruins and the population either scattered or exterminated. Others, minimizing the effect of German colonisation, actually minimize the effect of the Mongol invasion, stressing that the destruction was limited mainly to Lesser Poland and mainly the third Mongol invasion. Large numbers were taken prisoners. The refugees went north and helped to colonize the sparsely inhabited areas and to clear the forests to the east of the Vistula in Mazovia. On the heels of the receding Mongols came the Germans. Theirs was a movement along the line of least resistance. The new settlers were spared the hard labor of the pioneers as the soil they occupied had been used for arable purposes centuries before. There was no need of clearing primeval forest or colonizing an utter wilderness. On the other hand, Germans were also invited to settle territories which had been uninhabited before.
There is also a tendency to count all "locations in German law" as new German settlement. In fact, the German charter was considered more advanced than traditional Polish customs and therefore, soon, existing settlements received new rights based on the German charter (were relocated); also, many new Polish settlements were located using the German charter. It would be a mistake to think that all the newcomers were Germans. Especially in the eastern part of Poland many new towns were founded by Slavic tribes which at that time separated Poland from Germany, and the Germans who came to Poland went through this Slavic screen and brought with them numerous autochthons of the Slavic border lands. Upon arriving in Poland the settlers from the West restored agriculture, rebuilt the cities and came into possession of all the advantages the fertile soil and the favorable geographic position gave them.
The entrepreneur (known by the Latin name of villicator), who brought over a number of settlers, received, in addition to the compensation for his services, a piece of land for the colony of which he became the chief (woyt), with hereditary right to certain taxes. These rights he could concede or sell. He was also the judge of the colony. He was free from all duties except those of a knight and a tax collector, and responsible to nobody except to the Prince. The settlers, after dividing among themselves the land granted to them by the Prince, proceeded to build the city with its town hall, market-place and church in the center. The streets ran radius-like from the center. The town was surrounded by a mound and ditch, beyond which lay the arable fields, pastures and woods. The settlers were given every privilege of building the towns in the way to which they were accustomed, and to govern themselves according to the practice of their native country. For a number of years, varying in each case, the settlers were free from all taxes or duties. After the expiration of the term of years they had to pay a stipulated annual tax into the Prince's treasury. The tax was to be paid in cash, not like that of the Polish grody, in kind and services. In addition they were, in some instances, required to maintain defensive walls, towers and gates, and to supply impedimenta for war and armed servants. In their internal affairs they were given full home rule and were free from all interference by representatives of the Prince. They governed themselves according to German law, the woyt and a chosen jury constituting the court. Appeals from the decisions of this court could be taken to the Court of the Prince or to the higher courts in the German cities. The administration was in the hands of a City Council, consisting of the burgomaster and advisors, either elected by the people or appointed by the Prince, this depending on the terms of the charter. The artisans established guilds which regulated the quality and price of products. The Prince had the sole authority to grant town charters. Sometimes he gave this power to the feudal and ecclesiastical lords of the principality.
In this way beside the Polish "grody" sprang into existence a large number of towns, with German laws, customs and institutions. The ancient towns of Kraków, Lwów, Poznań, Płock and others received a large influx of Germans, and became regarded by the metropolitan towns in Germany as their branches and as outposts of German trade and civilization in Poland. The common law of the country was supplanted by the Magdeburg and Halle law, German silver coins became the money of the country, and all municipal records began to be kept in the German language. Had it not been for the Mongol invasion, Polish towns would have developed without interference and the cities' populations would have remained mainly Polish.
Similar to the growth of German towns was the development by colonization of villages based on German law. To induce settlers to come live in unoccupied areas, the Prince granted tracts of land exempt from taxes for a number of years. All the settlers on these lands were absolutely free. The only obligation was the payment of an annual rent to the Prince, collected for him by the organizer of the settlement, who, in compensation for his work, received in hereditary right a large grant of land, a flour mill or tavern. In addition to the duties of a tax collector the organizer, called soltys, was to render military service and act as the police officer of the village. He was also the presiding officer of the jury chosen by the villagers. In all administrative matters the village, like the city, had complete home rule. Except for the town hall and the town council the villages did not differ much from the towns. With the consent of the Prince, barons and prelates could either establish new free settlements or change the legal basis of the already existing native villages in their domains from the Polish to the German law.
On account of the advantages that the German method of settling gave to land owners, it became very popular and exercised a great influence upon the administrative, economic and particularly, political life of the country. In the beginning of the 13th century the Teutonic Knights settled on the Baltic seacoast on the invitation of duke Konrad of Masovia engaging in a crusade against autochthonous heathenish Baltic Prussians which led to further immigration of German and Flemish settlers in these countries.
An additional foreign element began to settle in Poland in great numbers at the same time. The Jews, persecuted all over Europe during the Crusades, fled to Poland where they were received in a most hospitable manner. They settled in the towns and began to carry on commerce and banking. An illustration of Poles' friendliness towards these newcomers is the statute of Kalisz, promulgated by Prince Boleslav in the year 1246 by which the Jews received every protection of the law, and which imposed heavy penalties for any insults to their cemeteries, synagogues and other sanctuaries. About the same time Prince Henry IV of Wrocław (Breslau) imposed heavy penalties upon those who accused Jews of ritual murder — this was a common anti-Semitic slander across Europe at the time. Anyone who made such an accusation had to prove it by six witnesses, three Gentiles and three Jews, and in case of his inability to prove the charge in a satisfactory manner he was himself found guilty and subject to severe punishment.
While the Jews adapted themselves to their new environment and coalesced, to a degree, with the native population, the German element, backed by their government, became aggressive and sought to dominate the country. The rich German townspeople were supported in their endeavors by the clergy, who arrived from Germany in great numbers and occupied prominent church positions. It was with the aid of the Germans that the dauntless but Germanized Leszek the Dark (1278–1288), and after him Henry Probus (1289–1290), ascended to the throne of Kraków. The German influence grew disquietingly. A strong antagonistic movement arose and the clash of the two forces constitutes the core of Polish history during the next century. The conflict resulted in complete Polonization of the German element; the descendants of these settlers were among the most ardent Polish patriots. The success of Polonization served as eloquent testimony to the great assimilative powers of the people and of the state building capabilities of the Poles.
Władyslaw I was succeeded by his son Casimir in 1333, who continued the work of his father. During his reign the country expanded its power over neighbouring areas. Many new castles were built and existing townships fortified. Thus, he became known as Casimir the Great. In foreign policy, Kazimierz the Great strengthened his country's position by combining judicious concessions to Bohemia and the Teutonic Knights with eastward expansion.
While using diplomacy to win Poland a respite from external threat, the king focused on domestic consolidation. He earned his singular reputation through his acumen as a builder and administrator as well as through foreign relations. Two of the most important events of Kazimierz's rule were the founding of Poland's first university, the Academia Cracoviensis in Kraków in 1364, making that city an important European cultural center, and his mediation between the kings of Bohemia and Hungary at the Congress of Kraków (also in 1364), signaling Poland's return to the status of a European power. Lacking a male heir, Kazimierz was the last ruler in the Piast line. The extinction of the dynasty in 1370 led to several years of renewed political uncertainty. Nevertheless, the accomplishments of the fourteenth century began the ascent of the Polish state toward its historical zenith.
Poland was in practice ruled by Louis' mother, Elisabeth of Poland (1305–80), dowager queen of Hungary, until her death in 1380. Louis survived his mother only by two years.
Jadwiga, queen of Poland (called also Saint Hedwig or Hedwig of Anjou) (1374 – 1399) succeeded her father, King Louis the Great on the Polish throne in 1384 following a two-year interregnum. Her reign saw the start of Poland's dynastic union with neighbouring Lithuania, and the latter nation's conversion to Christianity.
Both her mother, Elisabeth of Bosnia, and grandmother, Elisabeth of Kujavia, were descended from the Piast dynasty which had ruled Poland from IX century until 1370, and she was the granddaughter of King Ladislaus I, who had reunited Poland earlier in the century.
Jadwiga was betrothed to William of Habsburg. From the age of eight she lived at the ducal court in Vienna. Her father had also made an arrangement with Charles I of Bohemia, the Holy Roman Emperor for the latter's second son Sigismund to marry either Jadwiga or her sister Mary, later queen of Hungary (Sigismund married Mary.) Jadwiga had to return to Poland from Vienna when her sister Catherine died in 1378.
In 1381 the 13-year-old Sigismund, then Margrave of Brandenburg, was sent to Kraków by his elder brother Wenceslaus, King of the Romans, to learn Polish and to become acquainted with the land and its people, to preparing him to become its king together with Mary. Sigismund also was given Neumark to facilitate communication between Brandenburg and Poland.
When King Louis died in 1382, the Archbishop of Kraków crowned the younger daughter as "Jadwiga, King of Poland" — technically speaking, she was king, not queen. The nobility of Poland prevailed upon her to end her engagement with William and instead to marry Jogaila, Grand Duke of Lithuania, whose country had returned to paganism after a brief period of Christian kingship in the 1250s. In February 1386 Jogaila converted to Catholicism, and shortly afterward they were married. Jogaila was crowned king of Poland as Władysław, a name chosen in honor of Jadwiga's great-grandfather, the unifier. The regnal number for Władysław II Jagiełło is a much later invention.
Without question the most significant development of the formative era of Poland's history was the gradual absorption of the country into the culture of medieval Europe. After their relatively late arrival as pagan outsiders on the fringes of the Christian world, the Western Slavs were fully and speedily assimilated into the civilization of the European Middle Ages. Latin Christianity came to determine the identity of that civilization and permeate its intellect and creativity. Over time the Central Europeans increasingly patterned their thought and institutions on Western models in areas of thought ranging from philosophy, artistic style, literature, and architecture to government, law, and social structure. The Poles borrowed especially heavily from German sources, and successive Polish rulers encouraged a substantial immigration of Germans and Jews to invigorate urban life and commerce. From its beginning, Poland drew its primary inspiration from Western Europe and developed a closer affinity with the French and Italians, for example, than with nearer Slavic neighbors of Eastern Orthodox and Byzantine heritage. This westward orientation, which in some ways has made Poland the easternmost outpost of Latinate and Catholic tradition, helps to explain the Poles' tenacious sense of belonging to the "West" and their deeply rooted antagonism towards Russia as an iconic representation of an essentially alien way of life.