Well, history shows a lot of things. History also shows that a determined group of completely unarmed people can achieve victory over a heavily-armed force too. In other words, those with guns were conquered by those without guns. Whether that is possible or not depends on the level of determination of the unarmed force, and the goals of the armed force. If the goal is simple extermination, the guys with guns pretty much always win, yes. But if the goal is anything else (occupation, enslavement, whatever), then victory for the armed force is not at all guaranteed and really depends on how determined the unarmed force is to resist. This is how Gandhi and Martin Luther King won their respective battles: not with guns, but with sheer determination to thwart the goals of the armed forces oppressing them, at any cost except using violence themselves.

If you are an occupying force, and your goal is subjugation of the indigent population (for example), but that population disobeys your every order, what can you do? You can shoot them or bash their skulls in, of course (lots of Gandhi's followers died this way, not even ducking to avoid the killing blows rained upon them). But if the population still resists, then the goal of the occupying force is thwarted nevertheless, even if they have a hundred million guns and the oppressed population has zero. Britain vacated control of India not because those resisting them were heavily armed (they weren't armed at all), but because those resisting them were simply determined not to bow to British rule. In the face of that resistance, the British took their guns and left.

The human spirit can be far more powerful than mere guns.