Prince William and Prince Harry
Courtesy United for Wildlife
06/07/2014 AT 04:30 PM EDT
He might have only sent out his first Tweet
last month, but Prince Harry
has adopted the social media trend of holding up a sign to send a message.
The royal was supporting his big brother, Prince William
, as they held up placards to start the countdown to a new campaign to save wildlife.
William and ex-soccer star David Beckham
are set to unite in London on Monday to kick off a crusade that uses the power of sport to raise awareness of conservation issues.
On Friday, the princes signaled the launch of the #WhoseSideAreYouOn campaign by holding up the signs that simply show the date and are signed by each prince.
It is part of William's cause, United for Wildlife
, which he launched
The organization is a collaboration among seven of the world’s foremost conservation organizations and the Royal Foundation of the Duke and Duchess of Cambridge and Prince Harry. Aiming to engage and inspire young people at what the charities believe is a critical time, this latest campaign enlists the help of high-profile sports stars like Beckham and tennis star Andy Murray.