Think about it a bit. Make some calculated guesses as to what would have happened during and after the resistance if New Mexicans under governor Manuel Armijo had made an all out effort to resist the invasion by the Americans led by General Stephen Watts Kearny at the head of the American Army of the West. I am going to tell you that the result would have been a rout for the New Mexican defenders and a disaster for the survivors that would have remained as well as the rest of New Mexicans.
Other considerations for governor Armijo was the fact that there were a large number of Americans spies as well as pro American New Mexicans in the province. There was a lack, amongst New Mexicans, of guns, ammunition, food, discipline, drilled militia and finances to sustain a long drawn out war. Also, they could not count on Mexico City for reinforcements. All of this was known to governor Manuel Armijo and to Stephen Watts Kearny.
Governor Manuel Armijo also knew what Kearny had. How many horses, how many men and most important how many arms, and artillery. Armijo knew what the Americans could throw at the New Mexicans. It was a foregone conclusion to Armijo and to Kearny what would happen should New Mexicans resist the invasion.
A good portion of New Mexican men of fighting age would die in the effort. Armijo knew that and there is no doubt he took that into consideration. And we need to take into consideration the population of New Mexico at the time. It was about 40,000 Hispanic and probably not more than 10,000 Pueblo Indians. The non Pueblo Indians could not be counted as allies of the Hispanos or the Pueblos. Make an educated guess that out of 50,000 New Mexicans present 50% were women, 10% of the men would not be to participate because of advanced age and another 10% unable because they were too young and you get the picture. There would be fewer than 15,000 able bodied men capable of participating in a resistance to the American invaders.
Imagine an all out war in the defence of New Mexico with what we know. New Mexican male numbers would be reduced by 5,000 to 8,000 before they capitulated. The effect would have been a disaster to the province, a disaster to the Pueblo's and a disaster to Hispanic New Mexicans. The population of New Mexico would be changed forever. The people would be changed forever.
Governor Armijo knew that. He probably saved more New Mexican lives with the decision not to oppose the invasion than any other person, past or present.
Americans in New Mexico of the period were in reality spies, they had been carrying news back to the "states" of New Mexican strengths and weakness for over a quarter century. Americans were well aware that New Mexico and the northern part of Mexico were undefended and ripe for American expansionism.