Napoleon won gold in the 4×200-metre freestyle relay, silver in the 4×100-metre medley relay and bronze in the 100-metre butterfly whilst representing Australia at the Youth Olympic Festival. At the 2008 Commonwealth Youth Games in Pune, India, Napoleon won gold in the 200-metre freestyle, 4×100-metre freestyle, 4×200-metre freestyle, 4×100-metre medley relays as well as silver in the 100-metre freestyle. During the 2008 Oceania Swimming Championships held in Christchurch, New Zealand, Napoleon won gold in the 4×200-metre relay and bronze in the 200-metre butterfly. Napoleon won the national 1500-metre title and so became the sixth fastest Australian of all time at the 2009 Australian Swimming Championships.
Napoleon placed 9th in the 1500-metre, and was ranked 6th in the 400-metre freestyle at the Pan Pacific Swimming Championships. At the 2010 Commonwealth Games Napoleon won silver in the 400-metre freestyle in a time of 3.48.59, and gold as part of the 4×200-metre freestyle relay team.
Napoleon secured his place in his maiden Olympic team when he received 2nd place in the men's 400-metre freestyle at the 2012 Australian Swimming Championships. In both the heat and semi-finals of this event, Napoleon was to race against Australian swimming champion, Ian Thorpe who was making a comeback to swimming via this event. Despite both races receiving a high degree of media attention, Napoleon did not let this unnerve him. He swam impressively in his heat to become the top qualifier and later placed first in his semi-final race. To further cement Napoleon's Olympic dream, he placed 5th in perhaps what is the most competitive of the men's events, the 200-metre freestyle. This earned him a spot in the men's 4×200-metre relay team for the 2012 Summer Olympics in London. At the Olympics, he finished 8th in the 400 m freestyle, and was part of the Australian team that finished 5th in the 4 x 200 m freestyle.
Doping ban
After Napoleon qualified to contest in the 400- and 1500-metre freestyle at the 2010 Commonwealth Games in Delhi, swimming governing body FINA imposed a three-month doping ban on the swimmer due to results of a failed drug test taken in November 2009. Although FINA accepted an innocent mistake was made when Napoleon took incorrectly labelled asthma medication, it was decided that he would be ineligible for three months after the violation with the suspension commencing on 20 August 2010 meaning that he was unable to train with his squad and would be unable to compete in the games. Napoleon appealed the decision made by FINA to the Court of Arbitration of Sport resulting in the ban being back dated to 15 June 2010. Although he had missed out on vital training and preparation, Napoleon was then eligible to compete in Delhi where he claimed silver in the 400-metre freestyle and gold in the 4×200-metre relay.
