This past weekend marked 15 years since the September 11 terrorist attacks on the World Trad Centers and just like the rest of the world that morning, the Queen was seemingly shocked.

The tragic event saw her majesty take the bold move of breaking royal tradition and authorising the American anthem to play during Buckingham Palace's Changing of the Guard on Sept. 13, 2001.

“For the first time, the Queen allowed her troops to play The Star Spangled Banner, the national anthem of the United States, during the ceremony in tribute to the many who died,” wrote The Telegraph at the time.

“Standing beyond the palace railings, many of the 5,000 Americans broke down in tears and held their right hands over their heart in salute.”

One American witness at the ceremony, 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."

While it was over a decade and a half ago, the grainy footage of the royal’s gesture, and the people weeping at the Queen’s gates, is still powerful enough to send chills down the spine of anyone who can remember that historic day.

Photo: Queen Elizabeth II places a wreathe at Ground Zero on July 6, 2010 in New York to honor the victims of September 11, 2001 attacks on the World Trade Center | Getty

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