Middle East royalty watched yesterday as their sons joined Prince William at the Sovereign's Parade at Sandhurst.
William, an officer cadet, marched with 484 recruits at the military academy in Camberley, Surrey.
Among 236 cadets receiving their commission were the sons of the King of Bahrain and the ruler of Dubai.
King Abdullah II of Jordan represented the Queen, taking the salute of the recruits and inspecting cadets.
He told them: "Although we are trained in the profession of arms never forget you are soldiers, not warriors. And that armed conflict is always the worst and must be the very last way to settle disputes."
The king was a Sandhurst cadet 25 years ago and followed in the footsteps of his father and grandfather. He told the officer cadets: "You will have changed out of all recognition while here."
He added they would, "take up one of the most demanding but rewarding professions, the command of men and women who look to you when things go wrong. It is then your training and preparation will cut in."
He went on to tell 3,000 guests the story of how his father was described as an "idle king" by a sergeant and ordered to go and ask a statue of Queen Victoria in the academy grounds why he was being lazy.
The king added: "He was found fast asleep in his bed two hours later. When asked what he was doing he replied Queen Victoria told him he was a little tired and he should go and have a good sleep."
William, 24, has completed two-thirds of his officer training course and is expected to be commissioned as an Army officer in December.
His brother passed out from the academy in April and will join the Household Cavalry's Blues and Royals where he will serve in an armoured reconnaissance unit.
William, as an intermediate cadet, carried a SA80 rifle and showed how months of drilling had honed his marching skills.
The stature of the prince, more than six foot tall, meant he was placed at the end of a company.
As they marched past King Abdullah, first in slow time then in quick, William ignored the "eyes right" order barked out as he was the 'marker' helping to keep the cadets in a straight line.