And the said presidio mentioned above in said pre-l850 state, among others enslaved many in their 'missions', called 'assimilation'.

The Presidio was run by the Spanish and then the Mexican State, being staffed with military. The Missions were run by the Church and staffed Franciscans. Both used slave labor. Mariano Vallejo, the Mexican military commandant of Northern California, and later a California senator, ran a huge hacienda near Petaluma that used many Native Americans as slave labor. I believe he got them after they had been rounded up in the missions in San Rafael and Sonoma, baptized, and then farmed out. I'm not sure that they used the term assimilation, but perhaps conversation.

Ceci n'est pas un seing.