Happy birthday Prince William!

Kate Middleton's hubby, who turns 31 on June 21, is probably preparing for the imminent arrival of his first born rather than embarking on a pub crawl to celebrate his special day.

The future king is reported to be spending the day "privately" which probably means he will be with his Duchess and maybe even his rascally brother, Prince Harry. (Although if Harry had his way, he and his bro would be getting their drink on with royal partiers Princess Eugenie and Princess Beatrice.)

But no, Will will soon be a father to the third in line to the throne (even if the royal heir turns out to be an heiress), which means that he has responsibilities back at home.

Do those responsibilities include military service – again? Princess Diana's son, who serves as a Royal Air Force helicopter rescue pilot, has reportedly not decided whether to leave the RAF, join another military branch or leave completely although some reports claim that Will has told his superiors that he has decided to "move on."

So, just in case we never see the second in line to the throne in his dashing military outfits again, let's take a look at his best moments in uniform.

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  • Prince William

    Britain's Prince William talks to soldiers on November 14, 2010 before a remembrance day ceremony at Camp Bastion in southern Afghanistan. The prince flew into Afghanistan on November 14 for a surprise visit to honor Britain's war dead, as the Queen led the nation in remembrance in London.

  • Prince William

    Britain's Prince William talks to a member of the Afghan Army before a remembrance day ceremony on November 14, 2010 at Camp Bastion in southern Afghanistan. Prince William flew into Afghanistan on Sunday for a surprise visit to honour Britain's war dead, as the Queen led the nation in remembrance here in central London.

  • Prince William

    Britain's Prince William (C) poses for a group photo with the Royal Australian Regiment (RAR) third battalion at Holsworthy Army Barracks near Sydney on January 20, 2010. William will visit bushfire-ravaged areas near Melbourne on January 21 before returning home the following day.

  • Prince William

    British Prince William chats with soldiers during a reception at London Guildhall after a commemoration service to mark the recent end of British combat operations in Iraq, on October 9, 2009 in London. The Archbishop of Canterbury criticised policymakers for failing to properly consider the human cost of the Iraq war, at a ceremony attended notably by former British premier Tony Blair. In a service to mark the loss of 179 British troops in the conflict, Rowan Williams reminded his audience at London's St Paul's Cathedral of the divisions caused by the military campaign to depose Saddam Hussein.

  • Prince William

    Britain's Catherine, Duchess of Cambridge, smiles during a visit with her husband, Prince William (L), to attend a St Patrick's Day Parade at Mons Barracks in Aldershot, southern England, on March 17, 2013. Prince William attended the Parade as Colonel of the Regiment, and the Duchess presented the traditional sprigs of shamrocks to the Officers and Guardsmen of the Regiment.

  • Prince William

    Britain's Catherine, Duchess of Cambridge, and her husband, Prince William (Front 2nd L), pose for an official photograph as they attend St Patrick's Day Parade at Mons Barracks in Aldershot, southern England, on March 17, 2013. Prince William attended the Parade as Colonel of the Regiment, and the Duchess presented the traditional sprigs of shamrocks to the Officers and Guardsmen of the Regiment.

  • Prince William

    Prince William, Duke of Cambridge during the annual Trooping the Colour Ceremony at Buckingham Palace on June 15, 2013 in London, England. Today's ceremony which marks the Queens official birthday will not be attended by Prince Philip the Duke of Edinburgh as he recuperates from abdominal surgery and will also be The Duchess of Cambridge's last public engagement before her baby is due to be born next month. (Photo by Chris Jackson/Getty Images)

  • Prince William

    Prince Harry, Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge on the balcony of Buckingham Palace during the annual Trooping the Colour Ceremony on June 15, 2013 in London, England. Today's ceremony which marks the Queens official birthday will not be attended by Prince Philip the Duke of Edinburgh as he recuperates from abdominal surgery and will also be The Duchess of Cambridge's last public engagement before her baby is due to be born next month. (Photo by Chris Jackson/Getty Images)

  • Prince William

    Prince William Duke Of Cambridge attends the Trooping Of The Colour at Horse Guards Parade on June 16, 2012 in London, England. (Photo by Stuart Wilson/Getty Images)

  • Prince William

    In this handout image provided by the Ministry of Defence, Prince William, Duke of Cambridge (L) and his crew prepare for their first sortie of a six week deployment on February 4, 2012 in the Mount Pleasant Complex, Falkland Islands. Operating the Sea King Mk3 as part of 1564 Flight, their duties as part of the Royal Air Force Search and Rescue team include assistance to the vast array of shipping around the islands and mountain rescue, in addition to providing cover for the aviation assets based on the island. Flt Lt Wales is a fully qualified SAR helicopter pilot and this is his first overseas operational deployment. (Photo by Sgt Andy Malthouse/MoD via Getty Images)

  • Prince William

    Britain's Prince William, Duke of Cambridge, walks through Victoria Barracks in Windsor, west of London, on June 25, 2011, during a medal parade for the 1st Battalion Irish Guards Regiment. AFP PHOTO / POOL / CARL COURT (Photo credit should read CARL COURT/AFP/Getty Images)

  • Prince William

    Queen Elizabeth II is escorted by her grandson Prince William during a visit to RAF Valley where Prince William is stationed as a search and rescue helicopter pilot on April 1, 2011 in Holyhead, United Kingdom. The Queen toured the airbase meeting staff and families and was given a guided tour of a Sea King search and rescue helicopter by Prince William. (Photo by Christopher Furlong - WPA Pool/Getty Images)

  • Prince William

    Prince William walks to place a wreath on the memorial to the British Soliders killed in Afghanistan on November 14, 2010 during a remembrance day ceremony at Camp Bastion in southern Afghanistan. Prince William flew into Afghanistan on Sunday for a surprise visit to honour Britain's war dead, as the Queen led the nation in remembrance here in central London.

  • Prince William

    Prince William as Commodore-in-Chief-Submarines attends a ceremony to hand out silver and gold pins to sailors at HMNB Clyde naval base on October 28, 2010 in Faslane, Scotland. The presentation ceremony was held at Faslane, recently named as the future home of Britains submarine services. (Photo by Danny Lawson - WPA Pool/Getty Images)

  • Prince William

    Camilla, Duchess of Cornwall and Prince William arrive at Buckingham Palace during Trooping the Colour on June 12, 2010 in London, England. (Photo by Ian Gavan/Getty Images)

  • Prince William

    Britain's Princes William (L) and Harry stand during a photocall at RAF (Royal Air Force) Shawbury near Shrewsbury, central England, on June 18, 2009. Both princes are stationed at the Defence Helicopter Flying School training to fly helicopters. William is training to become an RAF search and rescue pilot while his younger brother Harry is aiming to become a pilot with Britain's Army Air Corps.

  • Prince William

    Prince William and Camilla, Duchess of Cornwall look out from the balcony of Buckingham Palace after the Trooping the Colour ceremony on June 13, 2009 in London, England. The ceremony of Trooping the Colour is believed to have first been performed during the reign of King Charles II. In 1748, it was decided that the parade would be used to mark the official birthday of the Sovereign. More than 600 guardsmen and cavalry make up the parade, a celebration of the Sovereign's official birthday, although the Queen's actual birthday is on 21 April. (Photo by Chris Jackson/Getty Images)

  • Prince William

    HRH Prince William trains with the Royal Navy at Britannia Royal Naval college June 3, 2008 in Dartmouth, England. The prince is spending the next two months with the Royal Navy following his completion of training with the Royal Air Force. The attatchment is designed to familiarize Prince William with the Structures capabilities and working conditions of the Royal Navy. He will take part in operations in the Caribbean on HMS Iron Duke. (Photo by Chris Jackson/Getty Images)

  • Prince William

    Britain's Prince William laughs during a training session, as he begins his two-month attachment with the Royal Navy at Britannia Royal Naval college, in Dartmouth, south west England, on June 3, 2008. The prince is an officer in the army but is also training with other parts of the British military, of which he will be commander-in-chief when he becomes king.

  • Prince William

    HRH Prince William is seen next to the Chipmonk aircraft his father flew when he was training at RAF Cranwell on the day of Prince William's RAF graduation ceremony on April 11, 2008 in Cranwell, England. Prince William's has completed a three month 'fasttrack' training course at the base and will move on to do a smililar course with the Navy. (Photo by Chris Jackson/Getty Images)

  • Prince William

    HRH Prince William and Prince Charles, The Prince of Wales stand in front of the original Chipmonk aircraft Prince Charles flew when he was training at RAF Cranwell on the day of Prince William's RAF graduation ceremony on April 11, 2008 in Cranwell, England. Prince William's has completed a three month 'fasttrack' training course at the base and will move on to do a smililar course with the Navy. (Photo by Chris Jackson/Getty Images)

  • Prince William

    (FILES) Prince William pulls off his glove after landing a Grob 115E light aircraft, known as the Tutor, while training at airbase RAF Cranwell, near Sleaford, Lincolnshire 17 January 2008. Britain's Prince William is to train as a search and rescue pilot, aiming to serve in the emergency services after being told he cannot be sent to Afghanistan, he said Wednesday September 15, 2008. William, second-in-line to the British throne, learned to fly with the Royal Air Force (RAF) earlier this year as part of military training which has also seen him spend time with the army and navy. AFP PHOTO/ADRIAN DENNIS/FILES (Photo credit should read ADRIAN DENNIS/AFP/Getty Images)

  • Prince William

    (FILES) Prince William walks across the tarmac on his way to fly a Grob 115E light aircraft, known as the Tutor, while training at airbase RAF Cranwell, near Sleaford, Lincolnshire 17 January 2008. Britain's Prince William is to train as a search and rescue pilot, aiming to serve in the emergency services after being told he cannot be sent to Afghanistan, he said Wednesday September 15, 2008. William, second-in-line to the British throne, learned to fly with the Royal Air Force (RAF) earlier this year as part of military training which has also seen him spend time with the army and navy. AFP PHOTO/ADRIAN DENNIS/FILES (Photo credit should read ADRIAN DENNIS/AFP/Getty Images)

  • Prince William

    Britain's Prince William (L) kisses his father Prince Charles as they depart the Royal Military Academy following the Sovereign's Parade in Camberley, west of London, 15 December 2006. Prince William was among the 446 officer cadets on parade, of which 227 passed out receiving their commision and becoming officers. Prince William is to join the Household Cavalry in The Blues and Royals. (Photo credit should read ADRIAN DENNIS/AFP/Getty Images)

  • Prince William

    Britain's Prince William (R) breaks into a smile as he is inspected by his grandmother Queen Elizabeth II, during the Sovereign's Parade at The Royal Military Academy in Camberley, 35 miles west of London, 15 December 2006. Prince William graduated as an army officer with a royal display of parade-ground skills Friday, in a traditional military rite of passage for the second in line to Britain's throne. In a black uniform completed with a red sash and clutching a gleaming assault rifle, 24-year-old William joined 227 fellow cadets in the passing-out ceremony at Britain's elite Sandhurst army academy southwest of London. His girlfriend Kate Middleton looked on beaming at the faultless display, attended by his grandmother Queen Elizabeth II and the rest of the royal family. (Photo credit should read ADRIAN DENNIS/AFP/Getty Images)

  • Prince William

    Prince William and Prince Harry stand side-by-side at the passing-out Sovereign's Parade at Sandhurst Military Academy on April 12, 2006 in Sandhurst, England. (Photo by Anwar Hussein/Getty Images)

  • Prince William

    Prince William attends the Army's Regular Commissions Board (RCB) selection process in October 2005 at Westbury in Wiltshire, England. Buckingham Palace announced today that Prince William will join the army next year as an officer cadet at Sandhurst military academy. (Photo Giles Penfound/Pool/Getty Images)

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