Confederate control over its claimed territory and population in congressional districts steadily shrank from three-quarters to a third during the course of the American Civil War due to the Union's successful overland campaigns, its control of inland waterways into the South, and its blockade of the southern coast. With the Emancipation Proclamation on January 1, 1863, the Union made abolition of slavery a war goal (in addition to reunion). As Union forces moved southward, large numbers of plantation slaves were freed. Many joined the Union lines, enrolling in service as soldiers, teamsters and laborers. The most notable advance was Sherman's "March to the Sea" in late 1864. Much of the Confederacy's infrastructure was destroyed, including telegraphs, railroads and bridges. Plantations in the path of Sherman's forces were severely damaged. Internal movement within the Confederacy became increasingly difficult, weakening its economy and limiting army mobility.