Vietnam was a non-linear war. There were no front lines with enemies on one side and friendlies on the other. Tactical problems could become very complex, with the enemy potentially in any or all directions. It was vital to be able to observe and fire 360 degrees all-around. Although atypical of most 20th-century warfare, those conditions were not necessarily unique to military history. Perhaps the closest American experience was the Indian Wars of the 19th
