On 24 October 1854, the allied forces of Britain, France, and the Ottoman Empire had settled in for a long winter's siege of the Russian port of Sevastopol. The British, under Lord Raglan, took Balaclava and the right flank of the siege. This was a problem, because the British didn't actually have the manpower to hold the right flank (see "Crimean War" re: rampant incompetence). Sensing weakness, Russian forces charged the British defences and managed to capture several redoubts and their artillery pieces. It was a major, though not ultimately significant, victory for the Russians, but the battle is most famous for the paean to incompetent leadership and senseless loss of life that is the Charge of the Light Brigade.
I'm sure you've read the poem (and if not, for God's sake go read a book): Cannon to the left of them, cannon to the right of them, etc. There were a lot of cannon, is the point. The whole thing is fraught with ambiguity and recrimination on all sides, but broadly, here's how it happened:
Lord Raglan, the overall commander of the British forces, gave the order to Lord Lucan, who commanded the cavalry forces, to send the Light Brigade to harry the Russian forces who had seized the artillery positions on the south side of the battlefield. Unfortunately, the courier who brought the order to Lord Lucan didn't deliver the information clearly enough, and Lord Lucan ordered Lord Cardigan, who commanded the Light Brigade (and was, incidentally, Lucan's brother-in-law and who hated him intensely), to charge a fortified Russian artillery position at the end of the valley.
(If you're beginning to notice a common theme of "Lord This" and "Earl of Suchandsuch" massively cocking up operations, you've hit upon the key problem with allowing bored aristocrats to buy officer's commissions.)
At any rate, despite this order making as much sense as "strip naked and dance the Argentine Tango within sight of the Russian guns to demoralize the enemy," Lord Cardigan duly led his men into the teeth of the enemy artillery. The net result was that the Light Brigade suffered roughly 40% casualties, the Russians were very confused, and Lord Cardigan, upon seeing that the battle was lost, buggered off back to his private yacht for steaks and champagne.
It was that sort of war.