Before the Battle of Chancellorsville, local Unionists within Confederate lines provided intelligence that proved crucial in the Chancellorsville Campaign. Loyalists Ebenezer McGee and Isaac Silver used remarkably simple methods: Silver observed Confederate camps and gathered information about the location and strength of various units, then wrote his reports in pencil without a cipher and passed them to McGee. McGee carried the reports across the Rappahannock to the Union army. The information was especially valuable in the virtually impenetrable Wilderness. Silver continued this work until the end of the war, while McGee was fatally wounded serving as a scout in 1864.