Career
Mexican–American War
Dennis Gahagan was born c. 1817 in Ireland. He emigrated to the United States in the early 1840s. He joined the United States. Army, which was recruiting for the Mexican-American War.
He arrived in San Diego by 1849 as a soldier with the First United States. Artillery (Magruder"s Battery).
He and his fellow troops fought and patrolled in the Southern California countryside during the Mexican–American War. United States. territorial period
In 1849 Gahagan was elected United States. Judge of the 1st Instance of the District of San Diego.
From 1849 to 1850 Gahagan was an Alcalde (Mayor) of San Diego.
