As the United States mourned after the Sept. 11, 2001, attacks, Great Britain responded with a powerful gesture that resonates to this day.

Watch (above) as Buckingham Palace's Changing of the Guard on Sept. 13, 2001, honored America by playing "The Star Spangled Banner."

"As the band of the Coldstream Guards began the US national anthem hundreds in the crowd sang along while others wept, before observing a two-minute silence," The Guardian wrote at the time.

One woman who was there, Jenny Lee, of San Francisco, told the Telegraph: "I was really touched that the Queen has done this. Even though I'm so many miles from home, I feel that Britain is really with us on this one."

You'll note in the grainy footage, now making the rounds on the Internet, that many wept.

Thirteen years later, you may want to do the same.