A heavy brigade is a formation made up from 'Heavy' Cavalry; i.e. Dragoon Guards and Dragoon

Dragoon

The word dragoon originally meant mounted infantry, who were trained in horse riding as well as infantry fighting skills. However, usage altered over time and during the 18th century, dragoons evolved into conventional light cavalry units and personnel...

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The Heavy Brigade was a British heavy cavalry unit commanded by General Sir James York Scarlett at the Battle of Balaclava

Battle of Balaclava

The Battle of Balaclava, fought on 25 October 1854 during the Crimean War, was part of the Anglo-French-Turkish campaign to capture the port and fortress of Sevastopol, Russia's principal naval base on the Black Sea...

 in the Crimean War

Crimean War

The Crimean War was a conflict fought between the Russian Empire and an alliance of the French Empire, the British Empire, the Ottoman Empire, and the Kingdom of Sardinia. The war was part of a long-running contest between the major European powers for influence over territories of the declining...

. The Brigade made a gallant uphill charge to defeat a superior force of onrushing Russian cavalry, an amazing instance of the triumph of the individual skill of the Victorian British soldier, as well as of British discipline and unit cohesion

Unit cohesion

Unit cohesion is a military concept, defined by one former United States Chief of staff in the early 1980s as "the bonding together of soldiers in such a way as to sustain their will and commitment to each other, the unit, and mission accomplishment, despite combat or mission stress"...

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At the Battle of Balaclava the brigade was composed of 2 squadrons each of the 1st Dragoons (The Royals), the 2nd Dragoons (Scots Greys), the 4th Dragoon Guards (Royal Irish), the 5th Dragoon Guards (Princess Charlotte of Wales's), and the 6th Dragoons (Inniskilling).