Final answer:
The corrected sentence is 'During World War I, Americans began singing 'The Star-Spangled Banner' at games.' Francis Scott Key wrote the anthem after the British bombardment of Baltimore, and it symbolizes unity and patriotism, especially during wartime.
Step-by-step explanation:
The corrected sentence for your history document could be:
During World War I, Americans began singing 'The Star-Spangled Banner' at games.
The Star-Spangled Banner became a patriotic symbol of strength and resilience for Americans, particularly during times of conflict. It was written by Francis Scott Key after witnessing the British bombardment of Baltimore during the War of 1812, and its powerful lyrics evoke the spirit of national unity and pride.
Though it was not officially designated as the national anthem until 1931, its presence at sporting events traces back to the World War I era, capturing the collective sentiment of a nation.