But to get those results, you had to remove the kids from home and isolate them in boarding schools, physically punish them if they spoke their native language, give them new names, and almost brainwash them into hating their culture. If you then got them to hide their background from their children and grandchildren, you were close to "victory".
Alternatively if you dilute people in a country of non-speakers it happens naturally without any force. Takes about three generations with (non-spanish*) immigrants to the USA.
-First generation speaks the new language as a second language and their original language as primary.
-Second generation grows up bilingual and speaks their "native" language to their parents and the new language to everyone else.
-Generation three is essentially monolingual.
*The spanish language community is large enough that speaking spanish continues to provide substantial utility aside from talking to your parents/grandparents.
