Fought during the American Civil War, Petersburg should never have been 'under siege' at all. Union forces should have seized control of the town in June 1864 but through a mixture of confusion and incompetence they failed in their objective and a yearlong siege followed. Petersburg is best remembered for the tragedy of the great crater, the result of a huge underground explosion in July 1864, into which the Union Army inexplicably charged, creating a ready made killing zone. This unusual tactic was an extreme answer to solving the problem of siege warfare.