Major General Robert Ross. The battle bought enough time for Baltimore's defenses to be strengthened. After advancing to the edge of American defenses, the British halted their advance and withdrew. With the failure of the land advance, the sea battle became irrelevant and the British retreated. At Fort McHenry, some 1000 soldiers under the command of Major George Armistead awaited the British naval bombardment. Their defense was augmented by the sinking of a line of American merchant ships at the adjacent entrance to Baltimore Harbor in order to thwart passage of British ships. The attack began on the morning of September 13, as the British fleet of some nineteen ships began pounding the fort with rockets and mortar shells. After an initial exchange of fire, the British fleet withdrew just beyond the range of Fort McHenry's cannons. For the next 25 hours, they bombarded the outmanned Americans. On the morning of September 14, an oversized American flag, which had been raised before daybreak, flew over Fort McHenry. The British knew that victory had eluded them. The bombardment of the fort inspired Francis Scott Key of Frederick, Maryland to write "The Star-Spangled Banner" as witness to the assault. It later became the country's national anthem. American Civil War Maryland's mixed sympathies Maryland was a border state, straddling the North and South. As in Virginia and Delaware, some planters in Maryland had freed their slaves in the years after the Revolutionary War. By 1860 Maryland's free black population comprised 49.1% of the total of African Americans in the state. After John Brown's raid in 1859 on Harper's Ferry, Virginia, some citizens in slaveholding areas began forming local militias for defense. Of the 1860 population of 687,000, about 60,000 Marylanders joined the Union and about 25,000 fought for the Confederacy. The political alignments of each group generally reflected their economic interests, with slaveholders and people involved in trade with the South most likely to favor the Confederate cause, and small farmers and merchants outside the major cities and in western Maryland allied with the Union. In the 1860 election, Lincoln received only one vote in Prince George's County, a center of large plantations. Beginning of the war The first bloodshed of the war occurred in Baltimore when the 6th Massachusetts Militia battled an attacking mob while marching between railroad stations on April 19, 1861. After that, Baltimore Mayor George William Brown, Marshal George