What happened at the battle of antietan?

Answer 1

5000 thousand men and another 18,000 were wounded.Lee was lucky to escaped but McClellan had intercepted a lost battle order,wrapped around cigars for each Confederate corps commander and inadvertently by a courier.But McClellan moved slowly ,failed to use large forces in simultaneous attacks all along the line,and allowed Lee's stricken army to retreat to safety across the Potomac.In the wake of Antietam, Lincoln removed McClellan from command.