When did the gallop stroke become popular in elite swimming?

The gallop stroke, also known as the Australian crawl, became popular in elite swimming during the 1920s. It was first introduced in the United States by Harold Hardwick, an Australian swimmer who competed in the 1912 Olympics. The stroke was popularized by Duke Kahanamoku, an American swimmer who won multiple Olympic gold medals. The gallop stroke was faster and more efficient than the traditional breaststroke, and it soon became the preferred stroke for competitive swimmers. Over time, the stroke was refined and perfected, leading to even greater success for its practitioners.