On April 18, 1862, advancing Federal forces reached the banks of the Rappahannock River, and African-American slaves realized that this armed presence altered their accustomed social controls, prompting many to take the initiative to escape bondage. A Fredericksburg slave named John Washington crossed the river to freedom directly in front of this location and later recalled that a soldier assured him he was now a free man. Many former slaves, including Washington, found work with the Union army as teamsters, cooks, and servants, while others continued elsewhere. By late summer, when the Union force withdrew to campaign in more distant places, at least 10,000 former slaves had moved through Stafford County toward freedom and an uncertain future. The Union army returned to Falmouth in November 1862, and although Federal troops were defeated at Fredericksburg that December, they remained encamped in Stafford County. When the Emancipation Proclamation took effect in January 1863, another exodus of African-Americans sought freedom through the Northern lines.