Prince William is inspected by his grandmother, Queen Elizabeth ll, as he takes part in the Sovereign's Parade at the Royal Military Academy Sandhurst on December 15, 2006 in Sandhurst, England. Credit: Anwar Hussein/Getty

As Queen Elizabeth celebrated her Diamond Jubilee (60 years on the throne), many are looking back at her reign -- including her grandson Prince William.

On, William, 29, recounts the time that his grandmother was present during his officiation at the Royal Military Academy on December 15, 2006. The pair are pictured in the photo above where William, who is supposed to be maintaining a stoic demeanor, cracks a smile as his grandmother, now 86, passes by.

"Taking part in the Sovereign's Parade at Royal Military Academy at Sandhurst is a moment I will never forget," he writes. "After a very demanding 44 week course, it was a memorable celebration of personal and collective achievement for everyone concerned. I felt especially proud to receive my commission as an officer in front of my grandmother, The Queen. She has been an incredible role model to me over the years, so it was very special to have her present for my graduation. I know it was also a memorable moment for my fellow officers to take part in the Parade in front of The Queen as Head of the Armed Forces."

The royal, who is a search and rescue pilot today, continues: "I remember The Queen's words as she addressed us from the tremendous parade ground at Sandhurst: 'You must be courageous yet selfless, leaders yet carers, confident yet considerate.' These qualities of selflessness and duty are values that The Queen has continuously demonstrated over the last 60 years and are qualities that remain very important to me."

Also on hand to witness the occasion: the royal's now-wife, Kate Middleton.

The pair met in 2001 while studying at University of St Andrews and got engaged nine years later. They tied the knot on April 29, 2011.