How can people use thoughts to conquer other people?

There are different ways people can use thoughts to at least attempt to conquer other people.

One way to control or influence others with thoughts would be to sow seeds of doubt. That is often how professional fighters and even domestic batterers gain power over others. The other person thinks they are weaker than they are and lets their opponent take advantage of them.

The placebo effect is another example. An army was nearly defeated and the bugler was given the order to signal a refeat. He didn't know how to play the tune to signal a retreat and played Charge instead. The army became motivated thinking there were reinforcements, and that restored morale, and they fought as hard as they could and won a seemingly hopeless battle. So you can use thoughts to motivate your people to conquer a rival.

Another foreseeable way to attempt to conquer other people with thoughts would be to use the occult. If one has a strong enough aura, they might, in theory, be able to influence things using just thoughts, though there is no scientific proof of this.