in front of him, Early decided not to send his army against the fortifications around Washington until the next day. Early's invasion of Maryland had the desired effect on Grant, who dispatched the rest of the VI Corps and XIX Corps under Maj. Gen. Horatio G. Wright to Washington on July 9. As Lee wrote to James Seddon, the Confederate Secretary of War, on July 19: The steamships carrying the Union force started to arrive in Southeast Washington around noon on July 11, about the same time that Early reached the outskirts of Fort Stevens with the lead elements of his troops. Defense of Washington The city of Washington, D.C., prepared for the Confederate assault amid one of the worst hot spells in its history. It lasted 47 days without rain, with temperatures exceeding . The U.S. Congress and prominent residents left town to escape the heat as much as the impending Confederate advance. However, President Lincoln remained near the city, staying with his family at the Soldier's Home in present-day Northwest Washington, although a steamer waited on the Potomac to evacuate them if the situation became dire. Meanwhile, refugees from surrounding counties began to enter the relative safety of the city. Overall command for defense of the District was given to Major General Christopher C. Augur as commander of the XXII Corps. Major Generals Quincy Gillmore and Alexander McCook commanded the Northeast sector and the reserve post at Blagden Farm, respectively. Augur commanded 31,000 troops and 1,000 artillery pieces in 160 fortifications, batteries, and trenches. Eighty-seven fortifications were north of the Potomac (facing Early's approach) with 484 heavy guns and 13,986 men. Land was cleared surrounding the city to create open fields of fire. Six companies of the 8th Illinois Cavalry were stationed in front of the northern defenses. Despite the impressive array, Washington's defenses were unformidable. General John G. Barnard, Grant's engineering officer, noted that many of the troops were not actually fit for duty because they were new recruits, untried reserves, recovering from wounds, or worn-out veterans. Bernard estimated that instead of 31,000, the actual number of usable troops was around 9,600. The capital was more vulnerable to Confederate attack than it seemed since with around 10,000 troops, the Confederate army matched the effective Union troop strength. Union command structure The arrival of the VI Corps, about 10,000 men, brought desperately needed veteran reinforcements. It also added