The art of carrying out sieges had been brought to a very high level a century earlier. One of the best examples of a classic siege was that of Yorktown, Virginia, captured by George Washington, Count Rochambeau, and the combined French and American forces in 1781. But the Napoleonic Wars had brought about a marked bias toward the offense, and the art had languished. It resurfaced during the Civil War at a time when the powerful new weapons of both sides combined to make sieges both longer and more costly in terms of casualties.

The Union was far in advance of the Confederacy in this regard. The Dahlgren gun, the Parrot cannon, and all sorts of mortars would be employed in the Siege of Petersburg. There were times when the regiments of the Army of the Potomac merely provided cover for the engineers, artillerists, and other siege specialists.