a river in northern Italy, a left-bank tributary of the Po River. It is 313 km long and its drainage area is 8,000 sq km. Its source is Lake Cancano in the Rhaetian Alps. The upper part of the Adda flows through the Valtellina Valley, which is a glacial trough valley; it crosses Lake Como, then the foothills of the Lombardy pre-Alps, and finally flows through the Lombardy plain. The Adda is in high water in spring, summer, and fall. The average flowrate is about 250 cubic meters a second. Hydroelectric power plants are in operation on the river. Canals take off from the lower reaches of the Adda, including the 56–kilometer Martesana Canal to Milan.

Adda was the site of a battle on April 15–17 (26–28) during Suvorov’s Italian campaign of 1799, which was part of the war of the second coalition (England, Austria, Russia, and other countries) against France. The Russian and Austrian troops, under the command of Field Marshal A. V. Suvorov (about 43,000 men) fought against the French troops, which were commanded first by General Scherer and later by General J. V. Moreau (about 28,000 men). Suvorov took advantage of the fact that the French front was overextended and diverted the attention of the French troops with the actions of the corps of General P.I. Bagration, who occupied the city of Lecco on April 15 on the right flank; after that the allies forced the Adda on April 16 in the center of the French positions and inflicted a severe defeat on the enemy in the two-day battle. The French army had 2,500 men killed or wounded and 5,000 taken prisoner, and the allies lost about 2,500 men. The victory on the Adda prepared the later successes of the allied troops in Italy.