Northern Expedition, in modern Chinese history, the military campaign by which the Kuomintang party overthrew the warlord-backed Beijing government and established a new government at Nanjing. At the outset of the campaign in July, 1926, the Kuomintang controlled only Guangdong and Guangxi provs. It was allied with the smaller Communist party and was receiving aid from the Soviet Union. Communist activists spread out across SE China, fomenting strikes and thereby weakening the enemy's rear. By Mar., 1927, the Kuomintang armies (swelled by the defection of intact enemy units) had pushed back the warlord armies of Wu P'ei-fu and Sun Ch'uan-fang and had taken all of SE China including the economic centers of Wuhan and Shanghai. At this point, a struggle broke out between the right-wing Kuomintang commander in chief, Chiang Kai-shek, and the left-wing-controlled provisional government at Wuhan under Wang Ching-wei. Arguing that Communist activities were socially and economically disruptive and would slow the primary task of political unification under the Kuomintang, Chiang launched a purge of Communists. When he was stripped of command (Apr., 1927), Chiang formed a rival regime at Nanjing. Finally, in July, 1927, the Wuhan government also broke with the Communists, and in Feb., 1928, the two factions reunited at Nanjing under Chiang's leadership. The Kuomintang renewed the offensive against the remaining northern forces (notably the army of Chang Tso-lin). Beijing was taken by the Kuomintang in June, 1928, and the national government was moved to Nanjing.

Lewis and Clark expedition, 1803-6, U.S. expedition that explored the territory of the Louisiana Purchase and the country beyond as far as the Pacific Ocean.

Purpose

Thomas Jefferson had long considered the project of a western expedition, having encouraged John Ledyard when he proposed such an expedition in the 1780s, and as president he contemplated the matter in earnest and discussed it with his private secretary, Capt. Meriwether Lewis. When Congress approved the plan in 1803 and appropriated money for it, Jefferson named Lewis to head it, and Lewis selected William Clark as his associate in command. The purpose was to search out a land route to the Pacific, to strengthen American claims to Oregon territory, and to gather information about the indigenous inhabitants and the country of the Far West. Before the long march was begun, the Louisiana Purchase was made, increasing the need for a survey of the West.

The Expedition

The men were gathered and in the winter of 1803-4 were trained in Illinois across the Mississippi from St. Louis, the starting point. In May, 1804, they set out up the Missouri, and the next winter was spent at the Mandan villages (near present Bismarck, N.Dak.). In 1805 the hardest part of the journey was made. After reaching the Three Forks of the Missouri River (and naming the three branches after Jefferson, Madison, and Gallatin in loyalty to the administration), they followed the Jefferson as far as they could. Then their Shoshone guide, the remarkable woman Sacajawea, helped to obtain horses for them to continue across the high Rockies. They crossed the Continental Divide at Lemhi Pass and went over the Bitterroot Mts. through Lolo Pass. They had reached the land of westward-flowing rivers, and for part of their way they followed the Clearwater River down to the Snake River (long called the Lewis). The Snake took them to the Columbia River and they spent a miserable, rainy winter season in Fort Clatsop, a crude post they built on the Pacific coast.

In the spring they started back across the continent. In July, 1806, the party split for a time in order to explore as much territory as possible. Lewis went with a group down the Marias River, while Clark and most of the men descended the Yellowstone River; they were reunited on the Missouri at the mouth of the Yellowstone on Aug. 12, 1806. The party arrived in St. Louis on Sept. 23, 1806, and were greeted with much acclaim. The route of the expedition is commemorated by a series of sites along the Lewis and Clark National Historic Trail (see National Parks and Monuments, table).

The importance of the well-planned, well-executed expedition (only one person had been lost) was enormous. Although it was not the first transcontinental crossing in the north (Alexander Mackenzie had preceded them in a remarkable voyage), it opened vast new territories to the United States. Its influence on the history of the West is incalculable. Its results matched the efficiency and capability of its leaders.

Challenger expedition, British oceanographic expedition under the direction of the Scottish professor Charles Wyville Thompson and the British naturalist Sir John Murray. Taking place from 1872 to 1876, it opened the era of descriptive oceanography. The team sailed in the converted 18-gun corvette Challenger, the first vessel specifically equipped for general oceanographic research. The expedition cruised almost 69,000 nautical mi (130,000 km) in the Atlantic, Pacific, and Antarctic oceans, gathering data on temperature, currents, water chemistry, marine organisms, and bottom deposits at 362 oceanographic stations scattered over 14 million sq mi (36 million sq km) of ocean floor. Its major contributions, covered in a 50-volume, 29,500-page report that took 23 years to compile, included the first systematic plot of currents and temperatures in the ocean; a map of bottom deposits that has not been changed much by more recent studies; an outline of the main contours of the ocean basins, incorporating the discovery of the mid-Atlantic Ridge and the then record 26,900-ft (8,200-m) Challenger Deep in the Mariana Trench; the discovery of 715 new genera and 4,717 new species of ocean life forms; and the discovery of prodigious life forms even at great depths in the ocean.