In 1839, Eugene Duflot de Mofras, was assigned to the French embassy in Mexico City and instructed to visit the northwestern provinces of Mexico, report on potential commerce, observe U. S., British, and Russian interests, and determine feasibility of French posts in the region. In fact, his real mission was as much that of a spy, undertaking a reconnaisance of the West and assessing the relative strengths of the competing interests of the United States, England and Russia, in the lands then claimed by Mexico, etc.
De Mofras visited Jalisco, Colima, Sinaloa, and Sonora in 1840, then sailed from Mazatlán to Monterey. He met with commandant Mariano Guadalupe Vallejo in Sonoma, continued to Fort Ross, and returned to Monterey in July. On September 1, he sailed up the Sacramento River with A.G. Rotchev, manager of Fort Ross, to New Helvetia, where he met with John Sutter, with whom Rotchev was to initiate negotiations for the sale of the Russian fort. He later visited San Jose, Santa Cruz, and San Francisco, before traveling to the Hudson Bay Company's Fort Vancouver. On this trip, de Mofras met and talked with Charles Wilkes. He returned to San Francisco with Hudson Bay Company director Sir George Simpson, factor John McLoughlin, and U.S. agent Horatio Hale, to Monterey. On January 3, 1842, de Mofras sailed via Santa Bárbara to San Diego, before returning to Mexico.
Duflot de Mofras provided important information on its economic life, foreign involvement, and geography. He provides excellent descriptions of the Russian posts at Ross and Bodega just prior to their sale to the United States. He specifically notes Sutter's willingness to serve France, and reports on the reputed plot of Isaac Graham to overthrow Mexican government in California.