The Chancellorsville campaign Military_operation began Process_start with the crossing Motion_directional of the Rappahannock River by the Union army on the morning of April 27 , 1863 .

That same day , Sedgwick advanced Self_motion across the Rappahannock River , defeated Getting the small Confederate force at Marye 's Heights in the Second Battle of Fredericksburg , and then moved Self_motion to the west .