In the morning, Major George Armistead raised a huge United States flag over Fort McHenry. American cannons and troops held off the British throughout the night, keeping them from advancing. This battle lasted for more than 24 hours, and cannons launched rockets high in the air over the harbor, lighting up the sky. The Royal Navy launched a naval attack while other British forces launched a land attack from the other side. This would be a huge blow for America, possibly even giving Britain victory of the whole war. The British knew that if they were able to capture Fort McHenry, they could take over Baltimore. Fort McHenry at the Baltimore Harbor was the last line of Baltimore's defense. The Baltimore Harbor in Maryland was an important seaport. The Second War for American Independence.Fires, Flight, Flag: The Story of the Star-Spangled Banner.This war is sometimes called the Second War of Independence. Britain's Royal Navy had also been engaging in the impressment of American seamen, which involved taking American seamen off of their ships and forcing them to work on British ships instead. The United States declared war on Great Britain on June 18, 1812, in response to Britain's restrictions on U.S. Francis Scott Key wrote the song during the War of 1812, as he watched cannons fire over Baltimore Harbor where the Chesapeake Bay and the Patapsco River meet. The United States' national anthem is "The Star-Spangled Banner." Even before the song became the country's national anthem, it was a popular patriotic song. " Star-Spangled Banner" History by Wizard Pins