Prince Harry, third in line to the British throne, has embarked on a military career, joining an elite but notoriously tough military academy on Sunday.

Prince Charles' 20-year-old son has enrolled at the prestigious Royal Military Academy Sandhurst in Surrey for a 44-week officer training course.

"I am really excited. I want to get on with it and do the best job I can do," Harry said in a statement issued through his father's office.

The prince and 270 other new recruits joining Sandhurst Sunday will face a gruelling schedule over the next few weeks.

"The first five weeks are going to be the toughest he's ever known," royal watcher Una Mary Parker told Canada AM Monday.

"He will be getting up at half past 6 every morning -- if not earlier, marching and walking to up 30 miles a day with a heavy pack on his back, digging trenches," she says.

Cadets are also expected to polish their own shoes and do their own ironing. They will live in modest quarters, furnished with a single bed, sink and wardrobe. They will not be allowed to leave the site of the academy or wear civilian clothing.

"The whole point about Sandhurst is character-building, learning to be disciplined, learning how to handle yourself above all as an officer and a gentleman," says Parker.

Major General Andrew Ritchie says Harry will learn the basics of being a good soldier. "They get a strong moral compass here," he explained.

"The moral dimension of being an officer in the British army is most important to us. Integrity, character and leadership training are probably the most important aspects."

After the course finishes, the prince, who will be addressed as "Officer Cadet Wales", will be eligible for active service.

Prince Charles accompanied his youngest son to Sandhurst Sunday. The pair chatted with army officials before Charles left, giving Harry a playful punch in the arm as a farewell gesture.

Harry follows a family military tradition. Prince Charles trained to be a pilot with the Royal Air Force, earning his wings in 1971 before going on to the Royal Navy. At one time, he commanded the minesweeper HMS Bronington. He left the service in 1976.

Harry's grandfather, Prince Philip, joined the Royal Navy in 1939 and commanded the frigate HMS Magpie. His naval career ended in 1952, when his wife became Queen Elizabeth II on the death of her father.

Harry's uncle, Prince Andrew, spent 22 years in the navy and saw active service while serving as a helicopter pilot in the Falklands War against Argentina.

Another uncle, Prince Edward, joined the Royal Marines but dropped out in mid-training.

Though British bookmakers are already taking bets that the young prince will not complete the 44-week course, Parker expects that Harry is embarking on what will be a successful military career.

"He's wanted to go into the army for many, many years. And he became the top cadet at his public school, Eton, in the junior army cadet corps," she says.

"It's the right thing for him to do, and I think he's going to do brilliantly."