 Mansfield, commander of the Department of Washington, argued that Northern Virginia should be occupied as soon as possible in order to prevent the possibility of the Confederate Army mounting artillery on the hills of Arlington and shelling government buildings in Washington.He also urged the erection of fortifications on the Virginia side of the Potomac River to protect the southern terminuses of the Chain Bridge, Long Bridge, and the Aqueduct Bridge.His superiors approved these recommendations, but decided to wait until after Virginia voted for or against secession.