Suddenly, without any warning, Jackson appeared at Manassas Junction. McClellan was at once ordered to transport his army by water to the Potomac, and place it under the orders of General John Pope, commanding the forces in front of Washington. McClellan did as he was ordered. But Lee moved faster than he could move. Before the Army of the Potomac was thoroughly in Pope's grasp, Lee attacked the Union forces near Bull Run. He defeated them, drove them off the field and back into the forts defending Washington (August, 1862).
杰克森率兵潜行，突然出现在马纳萨斯，麦克里兰立刻被命令将他的军队从水路转移到波特马克，服从华盛顿防卫军司令约翰o蒲伯的领导。麦克里兰服从了命令，但是李比他的行动还要快，在波特马克军全部到达蒲伯军队之前，李向布尔朗附近的联邦军队发动攻击，他打败了联邦军队，将他们从战壕中赶回到防护华盛顿的那些堡垒中（1862年8月）。
394. The Antietam Campaign, 1862.
394．安提塔姆战役（1862年）
Lee now crossed the Potomac into Maryland. But he found more resistance than he had looked for. McClellan was again given chief command. Gathering his forces firmly together, he kept between Lee and Washington, and threatened Lee's communications with Virginia. The Confederates drew back. McClellan found them strongly posted near the Antietam and attacked them. The Union soldiers fought splendidly. But military writers say that McClellan's attacks were not well planned. At all events, the Army of the Potomac lost more than twelve thousand men to less than ten thousand on the Confederate side, and Lee made good his retreat to Virginia. But McClellan was now removed from command, and Ambrose E. Burnside became chief of the Army of the Potomac.
此时李已经率兵穿过波特马克来到马里兰，但他遇到想象不到的抵抗。麦克里兰恢复了总司令指挥权，他将军队紧密地集结在一起，驻防在李的军队与华盛顿之间，并威胁李与弗吉尼亚的联系。南方联盟的军队撤退，麦克里兰发现他们坚守在安提塔姆附近并向他们发动攻击。联邦士兵英勇奋战，但是今天的军事评论家认为麦克里兰对战斗的计划有失妥当。在所有的战斗结束后，波特马克军损失12000多人，而南方联盟的军队损失不到10000人，并且李率兵成功撤退到弗吉尼亚。麦克里兰被撤职，由安布罗斯·E·伯恩赛德担任波特马克军的司令。