The military research tree in stronghold kingdoms is really what the game is all about. It allows you to build your military strength and take on both human and AI opponents. Archers are the first unit you should focus on in the game and thus in the research tree. But there are any other researches that can benefit you early on such as diplomacy and of course the researches to build you castle. If you don’t want to go down the honour building route early on you can start researching the military tree high straight away and build your honour by attacking AI opponents while completing quest and gaining other rewards.