The following units can be upgraded to SAM Infantry:
The SAM Infantry is useful if you can't afford an air force. It is also a good unit to keep if your enemy uses a lot of Gunships.
With the invention of the aircraft it quickly became apparent that mobile infantry units would need some kind of Anti-Aircraft weapons to defend against the new menace from the air. However, when flight was invented the idea that a single person could carry a rocket-based missile to destroy aircraft was unthinkable, and it took years before any were put into service. Throughout World War II, both sides in the conflict used rocket launcher devices in various forms. One form was the M1A1, an American made anti-tank rocket launcher that could be carried by infantry. By the late 1960s, several surface-to-air missile, shoulder fired single operator weapons were available. Many of these could hit an aircraft at over 10,000 feet off the ground. Even today these weapons are not as reliable as their designers had hoped, but when they do hit their target, it almost always results in devastating destruction.