although outnumbered two-to-one , lee committed Commitment his entire force , while mcclellan sent Sending in less than three-quarters of his army , enabling Preventing_or_letting lee to fight Hostile_encounter the federals to a standstill Change .

robert mcclellan of unk led the rising Change_of_leadership ; he gathered Come_together some men in dalry , led them to unk , where after a skirmish Hostile_encounter with other troops , he raised Bringing more men .

although he was being pursued Self_motion at a leisurely pace by maj. gen. george b. mcclellan 's army of the potomac , outnumbering Expansion him more than two to one , lee chose Choosing the risky strategy of dividing Cause_to_amalgamate his army and sent Sending one portion to converge Come_together and attack Attack harpers ferry from three directions .