Baseball was introduced to Guam by the United States Navy in the early 20th century

Baseball was introduced to Guam by the United States Navy in the early 20th century, to assist in the “civilizing” of the CHamoru people, but in time it eventually became a beloved activity for the community.
 
Early US Naval Governors saw CHamorus as a backwards and uncivilized people and governed them in a paternalistic tone, often treating them like children. As one Naval Governor noted, teaching CHamorus to play an American pastime like baseball, would help them learn to follow rules and instill in them proper values. CHamoru language was also banned on fields and during play, as a way of reinforcing the anti-CHamoru language policies of the US Navy.
 
Baseball was also a means through which the US Navy could assert its racial superiority as early games showed US sailors and marines dominating CHamoru teams. During the Japanese occupation of Guam, the occupiers encouraged baseball games between CHamorus and those who were Japanese or part-Japanese, as a means of showing their own racial superiority.
 
Within a few years of its introduction, CHamorus quickly adopted baseball as one of their favorite pastimes, and were soon regularly defeating US military teams. For example, as was reported in the prewar “Guam News Letter” newspaper, on August 9, 1913, the Carabaos (a CHamoru team) pushed across two runs in the bottom of the sixth inning and three more in the bottom of the seventh to defeat the American Marines, 9 to 8, in a baseball game at the Plaza de España.
 
Evening during the Japanese occupation, CHamorus often easily defeated their occupiers in baseball games. The late, Tun Charlie Perez recalled working in a mine for the Japanese, when he and others were called away to play a game against the Japanese who were guarding them. The game took place at Bradley Park in Anigua, where the CHamorus crushed their captors in an embarrassingly lopsided score.