General William Baillie (c. 1595–1653) was a Scottish professional soldier who fought for the Dutch and later commanded a regiment under Gustavus Adolphus in Sweden.
[6] In 1645, he commanded the detachment sent from Alexander Leslie, 1st Earl of Leven's army against James Graham, 1st Marquess of Montrose.
Baillie then split his forces, planning to trap Montrose between his own troops and a detachment commanded by Sir John Hurry.
Baillie retained command but was now accompanied by a Committee of War headed by the Earl of Argyll.
During the Second Civil War, Baillie commanded the infantry in the Duke of Hamilton's ill-fated Engager invasion of England.