As soon as the news of the arrival of the Northern army at Fortress Monroe reached Richmond fresh steps were taken for the defense of the city.
Magruder soon found that it would be impossible with the force at his command to hold the line he had proposed, and a large body of negroes and troops were set to work to throw up defenses between Yorktown and a point on the Warwick River thirteen and a half miles away.
A portion of this line was covered by the Warwick Creek which he dammed up to make it unfordable, and erected batteries to guard the dams.
Across the intervening ground a weak earthwork with trenches was constructed, there being no time to raise stronger works; but Magruder relied chiefly upon the swampy and difficult nature of the country, and the concealment afforded by the forest, which rendered it difficult for the enemy to discover the weakness of the defenders.
He posted 6000 men at Yorktown and Gloucester Point, and the remaining 5000 troops under his command were scattered along the line of works to the Warwick River.

He knew that if McClellan pushed forward with all his force he must be successful; but he knew also that, if the enemy could be held in check for a few days, assistance would reach him from General Johnston's army.
Fortunately for the Confederates the weather, which had been fine and clear during the previous week, changed on the very day that McClellan started.

The rain came down in torrents, and the roads became almost impassable.

The columns struggled on along the deep and muddy tracks all day, and bivouacked for the night in the forests.

The next morning they resumed their march, and on reaching the first line of intrenchments formed by the Confederates found them deserted, and it was not until they approached the Warwick Creek that they encountered serious opposition.