From Britannica:
Battle of Alma, battle fought on September 20, 1854, the first major engagement of the Crimean War. The victory by the British and the French left the Russian naval base of Sevastopol vulnerable and endangered the entire Russian position in the war.
Commanded by Prince Aleksandr Menshikov, the Russians had occupied a position on the heights above the confluence of the Alma River with the Black Sea in southwestern Crimea, thus blocking the road to Sevastopol. In order to advance, the allied French and British army, which had some 60,000 troops to the Russians 37,000, would have to assault Telegraph Hill, and to the east, Kourgane Hill, both of which were topped with Russian redoubts, and which ranged in height from 400 to about 950 feet. The valley in between led to Sevastopol, but no advance would be possible, even with their numerical advantage, if the Russians held the two hills.
The allies landed on the Crimean Peninsula some 35 miles (56 km) north of Sevastopol on September 14. Suffering from dysentery and cholera, it would be six days before the armies headed south. It was at the Alma, the second of the east-west rivers north of the Sevastopol, where they enjoyed a prime defensive position, that the Russians decided to stand their ground on September 20.