With Allied forces settling in for a long siege of the coastal city of Sevestapol, the British, under Lord Raglan, took Balaclava and the right flank of the siege. Realizing the British were understrength, Russian forces charged the British defences and managed to capture several redoubts and their artillery pieces.
In an attempt to recapture the redoubts, Lord Raglan gave 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. Lord Lucan subsequently ordered his brother-in-law, James Brudenell, 7th Earl of Cardigan, to harry the Russian forces; unfortunately for the British, Lucan's messenger didn't deliver the information clearly enough. Lord Cardigan dutifully led the charge of the Light Brigade against a heavily fortified Russian artillery position at the end of the valley, resulting in casualties in excess of 40%.
The standing fast of a thinly-spread Scottish regiment, the Argyll & Sutherland Highlanders, against a Russian cavalry charge, is the origin of the modern phrase 'Thin Red Line', to describe the situation when bravado alone can result in an unlikely victory.