Complex sentence: What was needed was a means to deliver the shaped charge warhead from a distance, different approaches to this goal would lead to the anti-tank spigot mortar, the recoilless rifle and, from the development of practical rocketry, the rocket propelled grenade.
Split into simpler sentences: What was needed was a means of delivering the shaped charge warhead from a distance. Different approaches to this goal would lead to the anti-tank spigot mortar, the recoilless rifle and, from the development of practical rocketry, the rocket propelled grenade.