1912. The club's first major success was a 8-5 victory over Oldham in the Challenge Cup Final at Headingley.
1915/16 – 1916/17 Dewsbury’s success continued as they finished champions in the 1915/16 and 1916/17 seasons. This success attracted players and supporters to the club - they caused a sensation signing Lance Todd from Wigan for £400 (although he played only 11 times before the outbreak of WW1 which interrupted his playing career) – he is now perhaps better known for the trophy, given in his name, at the Challenge Cup Final.
1921/22. Dewsbury beat the visiting Australasian team of the Kangaroo tour of Great Britain 13–6 when a sizeable crowd watched the match at Crown Flatt. Arguably the Australians’ mascot – a baby kangaroo - had greatest impact. When the team arrived at the railway station, crowds of children were there to see the kangaroo – reportedly the first to be seen in the town!
1922. The Northern Union renamed itself the Rugby Football League and the club adopted the title of Dewsbury Rugby Football Club.
1929. Dewsbury had the honour of playing in the first Wembley Challenge Cup final, losing 13–2 to Wigan. Dewsbury, having won the first semi-final can claim to be the first team to have qualified for the Wembley Challenge Cup Final. It is reported that Dewsbury were asked by the RFL to play an open running game (as compared to their normal defensive strategy) to make the match a more attractive visual spectacle to the Wembley crowd – a change in style, which if true, arguably cost them the game.
Adapted from Dewsbury Rams - Wikipedia
More information available in “The Official History of Dewsbury Rugby League Football Club” (Scargill, Fox and Crabtree) chapters 6-7