After Finnish independence in 1917 the Cadet school was moved to Santahamina in Helsinki and in 1920 the premises were occupied by the Reserve Officer School of the newly formed Finnish defence forces. Today the main building of the Cadet school host the headquarters of the Reserve Officer School of the Finnish Army.
Hamina Cadet school was abolished in 1901 with the abolition of the separate Army of the Grand duchy of Finland as part of the Russification policy. The conscription of Finnish soldiers directly to various units of the Russian Empire was seen as illegal and unconstitutional in Finland. Finnish officers protested first in through mass resignations and later through through a strategy of disobedience, in what is now known as the Conscription strikes. Finally it was settled that the Grand Duchy of Finland would fulfil it's obligation to the common defence with a monetary compensation to the Russian Empire instead through the provision of conscripts.
Many of the officers from the Hamina Cadet school played an important part in the early independence movement of Finland both in the administration of the Grand Duchy as well as in active support of the resistance.
By 1917 when Russian empire broke apart and Finland gained its independence. As the highest ranking Finnish officer at the time Mannerheim was called by the Senate to organise the Civil Guard into a new Finnish army. Until early 1917 Mannerheim was a general in the Imperial Russian Army commanding Russian cavalry troops in the southern front. After the abdication of the tsar Nikolai II in March he had returned to Finland.
Some other former Hamina cadets such as Carl Enckell, Rudolf Walden and Hannes Ignatius would rise to the occasion, but their effect was due to individual abilities. Most reliable Finnish officers from Hamina were too old and retired from active duty to form an effective core for the new Finnish army.
The field command of the new army had to be formed from the members in the Finnish Jäger troops. These were men who had travelled as individuals to Germany 1915-1917 to receive training in the German army in order to liberate Finland. Jäger troops had fought against the Russian empire. Those Finnish officers who had continued to serve in the Russian army were seen unpatriotic and considered unreliable by the Jäger.
Therefore at first there was a certain degree of distrust between Mannerheim's headquarters and the younger, mainly Finnish speaking, generation of Jäger officers. However the differences never surfaced during the war of 1918. After the Whites' victory in that war, Mannerheim resigned as Commander-in-Chief, dismayed at the increasing German influence in Finnish military and political affairs.
After the fall of the German Empire later in 1918 the background of individual officers lost it's political significance. Mannerheim was called in to be the Regent of Finland. Army of Finland and the Civil Guard were organised by Mannerheim and Walden as the minister of defence. However jäger officers continued to form the basis of the officer core.
Field Marshall Mannerheim was a cadet in the Hamina cadet school. Due to diciplinary breach he was expelled in his final year in 1886, which caused him to continue his military career in the Imperial Russian Army.
Carl Enckell, a politician, officer and a diplomat, graduated as an officer from Hamina Cadet School after which he served in the Imperial Russian Army learning fluent Russian. In 1917 Enckell negotiated for Finnish independence in Saint Petersburg in the position of Finnish Minister Secretary of State and representative of Senate of Finland. Later he served Finland on several occasions as the minister of foreign affairs and as the Finnish delegate in League of Nations.
General Rudolf Walden received his military education in Hamina Cadet School 1892-1900. He was the best of his class. Walden was dismissed from service in 1902, in connection with a conscription strike. After leaving the army Walden created a brilliant career in business.
General Hannes Ignatius received his military education in the Hamina Cadet School 1885-1892, and in the Nicholas Academy of General Staff in St Petersburg 1896-1899. Served in the Finnish Dragoon Regiment 1892-1901 after which he was as a businessman.