The Union formed in 1861 when several southern states seceded and formed the Confederacy in order to protect the institution of slavery. The Union states were represented by dark blue on maps and fought to prevent the south from forming their own country. Key events for the Union included the First Battle of Bull Run and the Emancipation Proclamation, which freed many slaves who then fought for the Union army. The Union wore blue uniforms and used muskets primarily. Under the leadership of President Lincoln and General Grant, the Union defeated the Confederacy and preserved the United States as one country.