During the American occupation of the state, the number of Indian attacks was drastically reduced, but in 1848 the attacks resumed to such a degree that the Mexican officials had no choice but to resume military projects to protect Mexican settlements in the state. Through the next three decades the state faced constant attacks from indigenous on Mexican settlements. After the occupation the people of the state were worried about the potential attack from the hostile indigenous tribes north of the Rio Grande; as a result a decree on July 19, 1848, the state established 18 military colonies along the Rio Grande. The new military colonies were to replace the presidios as population centers to prevent future invasions by indigenous tribes; these policies remained prominent in the state until 1883. Eventually the state replaced the old state security with a state policy to form militias organized with every Mexican in the state capable to serve between the ages of 18 and 55 to fulfill the mandate of having six men defending for every 1000 residents.