He was named Secretary of War during Juan Rafael Mora Porras's presidency in 1849 and eventually became Governor and Commander of Puntarenas in 1850.

[6] Named as a general in 1856, he commandeered the Costa Rican Army[6] during the third and most important part of the campaign against filibuster William Walker.

Cañas was also responsible for the development of Costa Rica's Pacific Ocean port, Puntarenas, where he served as commander for several years.

Years after Cañas's death, his children were still well received in Puntarenas by members of the thriving Chinese-Costa Rican community.

[11] Juan Rafael Mora Porras was executed by firing squad on September 30; Cañas was killed using the same method on October 2, 1860.