James Thomas Brudenell was born on October 16, 1797 in Hambledon, Buckinghampshire, England. He was educated at Christ Church, Oxford, and entered the army in 1824, at a later age than usual. He purchased promotion, becoming lieutenant colonel of the 15^th Hussars by 1832.

A martinet of uncertain temper, he quarreled with his officers, illegally placing one in arrest and was censured by the ensuing court material and was forced to give up his command in 1834. But in 1836 his family influence secured another command, this time of the 11^th Light Dragoons (renamed 11^th Hussars in 1840). He inherited his father's earldom and fortune in 1837, by spending an estimated £10,000 a year from his own purse he made the regiment the smartest in the service, and introduced what came to be called the Cardigan jacket. Again, his level of severity with his officers led to trouble and he dueled with one of them, Captain Harvey Tuckett, who was wounded.

Cardigan faced public anger by demanding trial by his peers and won his case on a technical point of law. he retained command of his regiment until his promotion to major general in 1854.

The Crimean War saw Cardigan appointed commander of the Light Brigade as a subordinate of his brother-in-law, 3^rd Earl of Lucan, with whom he was on bad terms. His Brigade saw little action before the celebrated Charge of the Light Brigade, during the Battle of Balaclava, which left the brigade decimated. Cardigan did query the ambiguous order, but did not hesitate when the order was repeated and led the maneuver steadily. Cardigan was lionized on his return to England and was appointed inspector general of cavalry. Later he sued Lieutenant Colonel Somerset J.G. Calthorpe who asserted in his book that Cardigan had not led the charge, but this was non suited on a technicality. He died from injuries on March 27-28, 1868, sustained in a fall from a horse.