Rule The World edged out joint-favorite The Last Samuri to win an emotional Grand National for Mouse Morris in a thrilling finish at Aintree Saturday, less than a year after the trainer's son Christopher died. Rule The World made up three lengths on The Last Samuri after the final jump to become the first horse to claim his first win over fences at the Grand National since the 19th century. Winning jockey David Mullins, just 19 years old, was making his maiden Grand National appearance, and he timed his charge to perfection. "It's unbelievable. I couldn't expect things to have gone any better, it all went to plan," he told Channel Four. "I'm very grateful for being given the chance to ride this horse." The Last Samuri, ridden by David Bass, looked to be on course for victory after being backed in to favorite spot alongside defending champion Many Clouds ahead of the race. But he was piped by the Michael O'Leary-owned Rule The World, who stormed back to win by two lengths to give trainer Morris, whose son died while travelling in Argentina, his first Grand National win. "I am delighted for Mouse, this horse has had two broken pelvises and he has brought him back each time," said RyanAir owner O'Leary. "It was a great ride by David Mullins. I am just lost for words and that does not happen for very often." First Lieutenant was the first to fall at the second, and champion trainer Paul Nicholls' Silviniaco Conti pulled up at the halfway mark. Willie Mullins' Sir Des Champs, with Nina Carberry on board deputizing for the injured Ruby Walsh, fell at the 15th fence. In a dramatic race it was set up to be a straight fight between the two favorites, but Many Clouds made a bad mistake at the fourth-last, just when he looked primed to become the first horse to make a successful defense since Red Rum in 1974. Instead it was Rule The World who came from third place behind The Last Samuri and outsider Vics Canvas after the 30th and final jump, to edge out Bass' mount in the final couple of furlongs. Only 12 of the 40 runners finished the four-and-a-quarter miles, but all the horses made it back to the paddock safely.