His first victory at Cheltenham was in the Broadway Chase, which he won by twenty lengths. Mill House beat Arkle when they first met in the 1963 Hennessy Gold Cup at Newbury, with Arkle slipping a few fences out and finishing third. However, in the 1964 Cheltenham Gold Cup, Arkle avenged that defeat by beating Mill House by five lengths to claim his first Gold Cup at odds of 7/4. It was the last time he did not start as the favourite for a race. Only two other horses entered the Gold Cup that year. The racing authorities in Ireland took the unprecedented step in the Irish Grand National of devising two weight systems — one to be used when Arkle was running and one when he was not. Arkle won the 1964 race by only one length, but he carried two and half stones more than his rivals. The following year's Gold Cup saw Arkle beat Mill House by twenty lengths at odds of 3/10. In the 1966 renewal, he was the shortest-priced favourite in history to win the Gold Cup, starting at odds of 1/10. He won the race by thirty lengths despite a mistake early in the race where he ploughed through a fence. However, it did not stop his momentum, nor did he ever look like falling. Arkle had a strange quirk in that he crossed his forelegs when jumping a fence. He went through the season 1965/66 unbeaten in five races. Arkle won 27 of his 35 starts and won at distances from 1m 6f up to 3m 5f. Racing commentator Peter O'Sullevan has called Arkle a freak of nature — something unlikely to be seen again. Besides winning three consecutive Cheltenham Gold Cups and the 1965 King George VI Chase, Arkle triumphed in a number of other important handicap chases, including the 1964 Irish Grand National, the 1964 and 1965 Hennessy Gold Cups, the 1965 Gallagher Gold Cup, and the 1965 Whitbread Gold Cup. In the 1966 Hennessy, he failed by only half a length to give Stalbridge Colonist 35 lb. The scale of the task Arkle faced is shown by the winner coming second and third in the two following Cheltenham Gold Cups, while in third place was the future 1969 Gold Cup winner, What A Myth. In December 1966, Arkle raced in the King George VI Chase at Kempton Park but struck the guard rail with a hoof when jumping the open ditch, which resulted in a fractured pedal bone; despite this injury, he completed the race and finished second. He was in plaster for four months and, though he made a good enough recovery to go back into training, he never ran again. He was retired and ridden as a hack by his owner and then succumbed to what has been variously described as advanced arthritis or possibly brucellosis and was put down at the early age of 13. Arkle became a national legend in Ireland. His strength was jokingly claimed to come from drinking Guinness twice a day. At one point, the slogan Arkle for President was written on a wall in Dublin. The horse was often referred to simply as "Himself", and he supposedly received items of fan mail addressed to 'Himself, Ireland'. The government ownedIrish National Stud, at Tully, Kildare, Co. Kildare, Ireland, has the skeleton of Arkle on display in its museum. A statue in his memory was erected in Ashbourne Co. Meath in April 2014.
