During the in 1845, he was engaged by a sutler to be an interpreter for the United States Army. When the troops were dispatched to Santa Fe, Ceran Saint Vrain dispatched Abreu in advance to buy up the goods of competing sutlers for Saint Vrain so it could enjoy a monopoly with the United States. Abreu worked in a store for Saint Vrain in Santa Fe, and worked as an interpreter for the United States and in the winter of 1848-1849 delivered the United States. mail between Santa Fe and Fort Leavenworth, Kansas (a process which took 40 days).
During the he traveled to California in 1850-1851.
He at first worked in Mora, New Mexico and then at the Maxwell store in Rayado. In 1862, he acquired 20,000 acres (81 km2) of the land grant for his Abreu A history of New Mexico described the ranch house as "one of the most picturesque and attractive in New Mexico and is the scene of a most generous hospitality."
The family sold most of the ranch in 1911 after his death and was bought by Waite Phillips in the 1920s, who was to donate 35,857 acres (14511 km2) to the Boy Scouts of America in 1938.