The landing was north of Sevastopol, so the Russians had arrayed their army in expectation of a direct attack. The allies advanced and on the morning of 20 September came up to the Alma river and the whole Russian army. The position was strong, but after three hours,:424 the frontal attack had driven the Russians out of their dug in positions with losses of 6000 men. The Battle of the Alma had 3,300 Allied losses. Failing to pursue the retreating forces was one of many strategic errors made during the war, and the Russians themselves noted that had they pressed south that day they would have easily captured Sevastopol.
Try to answer this question if possible (otherwise reply "unanswerable"): How many men did the Russians lose after three hours?
6000 men