This chapter explains the techniques of modern land warfare. It describes the problems that soldiers faced as modern weapons and modern industry became widespread. The chapter focuses on the example of the First World War. It discusses the solutions that commanders in that conflict developed. The chapter also discusses how military thinkers of the 1920s, 1930s, and 1940s integrated new weapons and new tactics into higher levels of planning. It explores whether methods that emerged during the world wars of the twentieth century remain appropriate in the wars of the twenty first. Machine guns also had limitations. These weapons are, for instance, difficult to move. Heavier models also require support from crews of up to ten men. The deadliest new weapon of the early twentieth century was modern artillery. Airborne troops are those that land by parachute or glider. Airmobile troops have vehicles that allow them to land and take off repeatedly during a battle.