After reading a newspaper report about an unsuccessful attempt to swim the English Channel, Webb gave up his career in the merchant marine and dedicated himself to swimming full-time. Webb spent months training on the south coast developing his slow and steady breaststroke before making his first attempt to swim the Channel on 12th August. He made it over halfway across before rough seas forced him to abandon the attempt.
At just after 1pm on 24th August 1875, Webb dived off of the Admiralty Pier at Dover at set off. Cheered on by the passengers and crews of passing ships, he finally arrived near Calais after spending nearly twenty-two hours in the water swimming a zig-zag course of around 39 miles. He returned to Britain as a hero.
Fame brought fortune to Webb, but his generosity resulted in him returning to swimming. He took part in endurance races, but the strain was beginning to tell. In 1880 he embarked on another great stunt, swimming across the Niagara downriver from the Falls; unfortunately, the current proved too strong and Webb was drowned.