For the III Corps of the Union Army during the American Civil War, see III Corps (ACW). ----

The British Indian III Corps was the primary ground formation that took part in the Battle of Malaya in 1942. It was commanded by Lieutenant-General Sir Lewis "Piggy" Heath.

The British III Corps was formed in both World War I and World War II.

There were four formations in the Union Army designated as III Corps (or Third Corps) during the American Civil War.

III Corps was an Australian Army unit during World War II. It was responsible for the defence of Western Australia in 1942-45.

In the Napoleonic Wars, the French III Corps was a legendary unit commanded by Louis Nicolas Davout, a Marshal of the French Empire. The III Corps made its mark on European history from 1805 to 1809, when it repeatedly scored impressive victories single-handedly or in conjunction with other French forces. Napoleon called it "My tenth legion", in reference to Julius Caesar's finest unit, the X Equestris.