HMS Ajax was a 74-gun third rate ship of the line

Ship of the line

A ship of the line was a type of naval warship constructed from the 17th through the mid-19th century to take part in the naval tactic known as the line of battle, in which two columns of opposing warships would manoeuvre to bring the greatest weight of broadside guns to bear...

 of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

, launched on 23 December 1767 at Portsmouth Dockyard. She was designed by William Bateley, and was the only ship built to her draught.

She saw extensive action in the War of American Independence, taking part in the Battles of Cape St. Vincent

Battle of Cape St. Vincent (1780)

The naval Battle of Cape St Vincent, took place off the coast of Portugal on 16 January 1780 during the American War of Independence. A British fleet under Admiral Sir George Rodney defeated a Spanish squadron under Don Juan de Lángara. The battle is sometimes referred to as the Moonlight Battle,...

, the Chesapeake

Battle of the Chesapeake

The Battle of the Chesapeake, also known as the Battle of the Virginia Capes or simply the Battle of the Capes, was a crucial naval battle in the American War of Independence that took place near the mouth of Chesapeake Bay on 5 September 1781, between a British fleet led by Rear Admiral Sir Thomas...

, St. Kitts

Battle of St. Kitts

The Battle of Saint Kitts, also known as the Battle of Frigate Bay, was a naval battle that took place on 25 and 26 January 1782 during the American Revolutionary War between a British fleet under Rear-Admiral Sir Samuel Hood and a larger French fleet under the Comte de Grasse.-Background:When Hood...

 and the Saintes

Battle of the Saintes

The Battle of the Saintes took place over 4 days, 9 April 1782 – 12 April 1782, during the American War of Independence, and was a victory of a British fleet under Admiral Sir George Rodney over a French fleet under the Comte de Grasse forcing the French and Spanish to abandon a planned...

.

She was sold in 1785.