The Battle of Fishguard was a military invasion of Great Britain by Revolutionary France during the War of the First Coalition. The brief campaign, on 2224 February 1797, is the most recent landing on British soil by a hostile foreign force, and thus is often referred to as the "last invasion of mainland Britain".

The French general Lazare Hoche had devised a three-pronged attack on Britain in support of the Society of United Irishmen. Two forces would land in Britain as a diversionary effort, while the main body would land in Ireland. Adverse weather and ill-discipline halted two of the forces but the third, aimed at landing in Wales and marching on Bristol, went ahead.

After brief clashes with hastily assembled British forces and the local civilian population, the invading force's Irish-American commander, Colonel William Tate, was forced into unconditional surrender on 24 February. In a related naval action, the British captured two of the expedition's vessels, a frigate and a corvette.

Chef de brigade William Tate was the Irish-born American commander of a French invasion force known as La Légion Noire ("The Black Legion") which invaded Britain in 1797, resulting in the Battle of Fishguard.

In 1793, French Consul Michel Ange Bernard Mangourit wanted to capture Florida from Spain. He commissioned William Tate as a French Colonel to raise and lead a force of Americans. Tate was instructed to recruit from outside the United States, but he recruited from the region of the Carolinas, especially rural settlers. In February 1794, Jean Antoine Joseph Fauchet, arrived in Philadelphia as the new French ambassador, and rescinded Tate's commission.South Carolina threatened to arrest Tate for treason, and he fled to France in 1795, where he was given command of the Légion Noire during the 1797 invasion of Britain. The 1,200 to 1,400-strong Légion Noire landed at Carregwastad Point, near the Welsh port of Fishguard, on February 22 but surrendered three days later at the Battle of Fishguard. After brief imprisonment, Tate was returned to France in a prisoner exchange in 1798, along with most of his invasion force. This was the last invasion of the British mainland by foreign forces.

Tate reportedly held a grudge against the British because his family had been killed by pro-British Native Americans in the American War of Independence, and he advocated Irish republicanism.Many historians, following E. H. Stuart Jones, the author of The Last Invasion of Britain (1950), have suggested that William Tate was about 70 years old in 1797; he was in fact 44.