three o'clock in the afternoon
The frigates were stationed farther outward , the water being too shallow to allow them to approach within four or five miles of the city , or two and a half of the fort . `` Besides , the Americans had sunk twenty-four vessels in the narrow channel between Fort McHenry and Lazaretto Point , to prevent the passage of the vessels of the enemy . `` That night was spent by the British fleet in preparations for the morrow 's attack upon the fort and the entrenchments on the hill , and on the morning of the 13th their bomb-vessels opened a heavy fire upon the American works , about seven o'clock , and at a distance of two miles . They kept up a heavy bombardment until three o'clock in the afternoon . `` Armistead at once opened the batteries of Fort McHenry upon them , but , after keeping up a brisk fire for some time , discovered that his missiles fell short and were harmless . It was a great disappointment to find that he must endure the tremendous shower of the shells of the enemy without being able to return it in kind , or do anything whatever to check it . But our brave fellows kept at their posts , enduring the storm with great courage and fortitude .