Here is what would happen say the Governor and the State Legislature approved a session from the Union, they would order the State Militia to protect them. That would consist of State Cops, Texas National Guard, and a handful of other semi-military state units (a list http://en.wikipedia.org/wiki/Texas_Military_Forces ) All together they would have about 5-10k troops, they would have to order and rally them to service in the new independent Texas, big problem half of these troops will be under direct control of the US military, the other half is already deployed as peace keeping in Texas and on the states boarder. so they would need about 2-3 weeks to mobilize, also they would need new volunteers to boost their numbers, this could take as much as 6 - 20 weeks to establish and than an addition year of training for the new recruits. Mean while with in 6 hours after they signed the document separating themselves from the US they are all arrested by Federal cops and US military. They will then spend the next year in Jail as they face trail for treason, which still has a possible Death Sentence. Granted only the Governor and the leaders of the state house would face death the rest would get life in prison.