Trump has long admired the British royal family and his big birthday parade in Washington is the same day as the U.K.’s annual Trooping the Color.

A protest group has encouraged demonstrators to book up tickets to the military parade this weekend, in an effort to leave seats empty.

But with the event falling on June 14, President Donald Trump’s 79th birthday—and with his name, presence, and fingerprints woven throughout—the military spectacle has become one of the most controversial and polarizing public displays in the nation’s capital in years.