P.G.T. Beauregard began as a United States Army engineer, graduating from West Point in 1838 and serving in the Mexican-American War. His peacetime work included New Orleans harbour and customs-house projects. Briefly appointed superintendent of West Point, he left federal service when Louisiana seceded in 1861 and became one of the Confederacy's first general officers. His experience shaped Charleston's defences.

Acting under Confederate government orders, he demanded the evacuation of Fort Sumter and commanded the bombardment that opened the Civil War in April 1861. In July he shared leadership with Joseph E. Johnston at First Manassas, where Confederate forces defeated the Union army. Public acclaim followed, but disagreements with President Jefferson Davis over strategy and military administration repeatedly complicated his service.

Transferred west, Beauregard became Johnston's second-in-command and took charge at Shiloh after Johnston was killed in April 1862. The Confederate offensive failed to produce a decisive victory, and Union counterattacks forced a retreat. Beauregard subsequently evacuated Corinth in the face of a larger Union force and lost his western command. Returning to the Atlantic coast, he directed the defence of Charleston against naval attacks, bombardment and assaults on its fortifications in 1863.

In 1864 he defeated Benjamin Butler at Drewry's Bluff, helping confine the Army of the James at Bermuda Hundred. He then organised Petersburg's defence during the initial Union assaults in June, gaining time for reinforcements to arrive and protecting the approaches to Richmond. His later assignments included broad responsibility in the western theatre as Confederate resources collapsed. After the war he worked in railway management and became a paid supervisor and public promoter of the Louisiana State Lottery. These ventures brought financial security, while his writings continued disputes over Confederate strategy and defeat.