The allies had arrived in Crimea in a state that hardly promised victory. Their fleet had put an army ashore at Kalamita Bay on 14 September, and the disembarkation was a misery, especially for the British. Cholera moved through the ranks, and sick men had to be lifted from the boats. There were no wagons, so parties went out to take carts from local Tatar farms; there were no tents, so soldiers lay in the open through blistering days and drenching nights. Prince Menshikov, for his part, had been caught off guard, disbelieving that anyone would invade so near the onset of winter. Yet when the ragged allied columns finally turned south toward Sevastopol, roughly forty-five kilometers away, some sixty thousand British, French, and Ottoman troops were on the move, and Menshikov had barely half that number waiting on the heights.

The Russians had made one fateful assumption. The cliffs above the river mouth were so sheer, they reasoned, that no one could scale them, so they left that flank almost undefended by guns. The French Zouaves proved them wrong. Leaving their packs on the bank, they swam the river and hauled themselves up the rock face, using the trees for handholds, then held the plateau from behind boulders until reinforcements and a dozen guns were dragged up a ravine behind them. Menshikov rushed troops from his center to plug the collapsing left, but it was too late. Meanwhile the British, ordered to lie flat under Russian artillery while they waited for the French to break through, endured a long, deadly hour and a half before finally rising to cross the river and storm the redoubts on the Russian right.

The British assault was a shambles of jumbled regiments and broken formations, and their first rush into the greater redoubt was thrown back at bayonet point. What saved them was technology. Their Minié rifles could kill at ranges the Russian smoothbore muskets could not answer, and from the riverbank, marksmen picked off Russian gunners before the crews could work their pieces. Standing exposed on open heights, without trenches to shield them, the Russians simply could not endure it. Their line dissolved, and the retreat became a rout, men streaming away in leaderless knots toward the Kacha River. On Telegraph Hill the French found Menshikov's abandoned carriage, stocked with letters from the Tsar and fifty thousand francs. Near it lay the debris of the vanished audience: parasols, field glasses, the remains of interrupted picnics.

The reckoning was grim on both sides. The Russians lost around five thousand men, the British some two thousand, the French roughly sixteen hundred, the Ottomans five hundred. The victors were poorly prepared for their own success. With almost no medical supplies, the British took two days to clear their wounded, requisitioning supply carts to carry them, and about sixteen hundred injured men waited days for the ships that would take them to the overwhelmed hospital at Scutari, near Constantinople. The Russians, forced to leave their wounded behind, saw many limp back toward Sevastopol over the following days. The victory rang loud in Paris and London. The French raised the Pont de l'Alma over the Seine to mark it, and the name Alma spread across the world to bridges, rivers, and small towns from New Brunswick to New Zealand, carried far from the muddy river where so many had fallen.