Crossfire is extremely effective!
Crossfire is both Offensive and Defensive.
By “interlocking fire,” or lining up your weapons’ so the arcs of fire overlap, you make it extremely difficult for anyone to attack either of you.
Crossfire is difficult to hide from.
By setting up from two different angles, it is difficult for others to hide. If I hide from gun number one, gun number two is at a good angle to attack. If I hide from gun number two, gun one has an advantage.
Crossfire creates a “no man’s land” that is impossible to cross.
Lots of people have lost lives trying to cross this area.
Maybe, using armored vehicles, air support, indirect fire support, or stealth can overcome a defense. But if you use crossfire coupled with mines, snipers, and barbed wire, you become very difficult to beat.
Add air cover to the mix, and you become the impossible foe!
Crossfire is awesome at defending your front lines.
Machine guns were used during WWI to provide crossfire defense to the front of their trenches. They were called machine-gun nests and were incredibly nasty to anyone attacking the trenches.
This was probably a huge contribution to the success of trench warfare.
Use the ultimate crossfire defense in urban environments
Place people behind buildings on both sides of the choke point (entrance) where they could provide crossfire.
Add a few snipers on top, barbed wire around the entrances and a small front line with minor explosives and you have a recipe for awesome defense!