On September 17, Prince Harry will take part in a 24-hour Cold Chamber Training Exercise.  This is in preparation for the "Walking with the Wounded South Pole Allied Challenge" happening later this year which he and other military personnel would embark.

According to the "Walking With the Wounded" website:

Prince Harry, Patron of the Walking With The Wounded South Pole Allied Challenge, will take part in a 24-hour Cold Chamber Training Exercise with the rest of Team Glenfiddich: Captain Ibrar Ali, Sergeant Duncan Slater, Captain Guy Disney and Major Kate Philp, in Nuneaton, Warwickshire, on 17 September 2013.

The training, it explained, "aims to help the team acclimatise, test equipment and practice the routine for the South Pole, including skiing and setting up camp."

Walking With The Wounded is a non-profit organization that aims to help military service personnel who have been injured in the line of duty.  The website describes it:

Walking With The Wounded raises funds to train the Wounded, Injured and Sick, assisting them to find a career outside the Military. Whether suffering a physical or mental injury, whether a service leaver or veteran, we want to help provide our wounded with the future they deserve.

The "Walking with the Wounded South Pole Allied Challenge" will involve three teams - Team Commonwealth (Australia and Canada), Team UK, and Team US - who will go on a 16-day expedition way down south.  They will traverse 335 kilometers of harsh conditions at -35 degrees C, and aim to reach the South Pole by December 17. 

The teams, all composed of wounded military service personnel, will fly to Antarctica in November.

The website further explains:

Our expeditions are held to raise awareness, to show the public who our wounded are, to tell their stories, to highlight the support they need. They are also to champion these extraordinary people who do not give up despite injury, who continue to face challenges with determination and courage.

As Prince Harry focuses on this challenge, beau Cressida Bonas would have to stay behind to cheer him and his everyone on.