I have heard the argument from both pro and anti gunners that civilians would be "no match" for the mighty US military. I try to avoid mall ninja-type conversations, in general. But I think it's easy to say that, because our military has many advantages over civilians, that somehow that translates into a hopeless defeat.
It would be wildly unlikely that there would somehow be a war between the US military and it's civilian population. But...(Coach dons his mall ninja hat) Say the president passed an executive order that banned all firearms and required the confiscation of all privately owned firearms, and the military faithfully obeyed this order to a man. Short of levelling every city and town, I doubt very much they could disarm Texas, let alone the entire country. Not before they either ran out of people, or ran out of will. Think of the logistics! Plenty of people would hand over their firearms, no doubt. But many wont. So it would be urban warfare, house to house...apartment to apartment... tens of thousands of barricaded, armed individuals. Ask a person who has actually been in combat if they thought the military could forcefully disarm the entire US population. They would laugh at you.