The people of the city of Alexandria were generally infected with disloyalty, and rebel flags floated boldly from many of the principal buildings. A detachment of Confederate troops was at all times quartered within its limits, and with the hope of capturing them and their supplies, it was determined to occupy the city by a surprise movement. The result of the election clearly foreshadowed, arrangements were made for action—prompt and decisive action—to follow immediately upon the closing of the polls, where disunionists had played a mere farce, and disloyal bayonets had fettered the freedom of the ballot-box. On the night of May 23d, orders were given for an advance to the troops designed for this expedition, numbering in all about 13,000, and at ten o’clock an advance guard of picked men moved cautiously over the bridge. Sent to reconnoitre, their commands were imperative that if assaulted they were to signalize for reinforcements, which would be speedily furnished by a corps of infantry and a battery. At twelve o’clock the regiment of infantry, the artillery and the cavalry corps began to muster, and as fast as they were prepared, proceeded to the Long Bridge, the portion of the force then in Washington being directed to take that route. The troops quartered at Georgetown, comprising the Fifth, Eighth, Twenty-eighth and Sixty-ninth New York, also proceeded across the Chain Bridge, under the command of General McDowell. At half-past one o’clock, six companies of District Volunteers, including the National Rifles, and Turners, stepped from the Long Bridge upon Virginia soil. To capture the enemy’s patrols by the means of boats had been the original plan, but the bright moonlight prevented it. This vanguard was commanded by Inspector-General Stone, under whom Captain Smead led the centre, Adjutant Abbott the left, and Captain Stewart the right wing. When within half a mile of Alexandria, they halted and awaited the arrival of the main body. The remainder of the army crossed in the following order: The Twelfth and Twenty-fifth New York, First Michigan, and First, Second, Third, and Fourth New Jersey; two regular cavalry corps of eighty men each, and Sherman’s two batteries; next and last came the New York Seventh. General Mansfield directed the movements of the troops. At a quarter to four the last of the forces left, and fifteen minutes later Major-General Sanford, accompanied by his staff, proceeded to Virginia to assume the command. The famous Sixty-ninth New York, after crossing the river below Georgetown, took position on the Orange and Manassas Gap railroad, and surrounded and captured the train from Alexandria, with a large number of passengers, of which a few, known to be violent secession partizans, were retained as prisoners.