TANKS, IFVS, AND APCS
While many people talk about the need for an infantryman with a rifle, the fact remains that an infantryman brings very little relative firepower to the table. On the ground, much of the firepower on the front lines comes from tanks, infantry fighting vehicles, and armored personnel carriers.
One cannot really fight a war without these, especially on the ground. These vehicles can often provide protection, transportation, and fire support. The tanks, APCs, and IFVs in service today are proven veterans.