against the war. from his camp in virginia, he plans to march his army across the potomac, into the peaceful northern territory of pennsylvania. as lee marches north, union general joe hooker resigns. for president lincoln, whose generals have already lost battles at fredericksburg, second manassas, and chancellorsville, hooker's sudden resignation is another unwanted headache. [ all shouting ] [ gun cocks ] >> with his army in turmoil and the union in jeopardy, president lincoln seeks solace in the company of his oldest son, robert. >> this war is a continual trial. rebel troops are marching north again, and the