Buffalo Bills fullback Corey McIntyre shows his game face in front of Marines serving with the 13th Marine Expeditionary Unit just before the singing of the national anthem at Candlestick Park, Oct. 7, 2012. U.S. Marines, sailors, coast guardsmen and members of the Royal Canadian Navy marched on to the field to salute during the singing of the national anthem. The service members received a standing ovation as they left the field.