phalanx
the ship seemed doomed, but the phalanx system came online just in time to shoot down the anti-ship missiles
a 20mm 6 barreled anti-missile ciws (close-in weapons system)  mounted on aircraft carriers and other ships
"the ship seemed doomed, but the phalanx system came online just in time to shoot down the anti-ship missiles" What is the definition of "phalanx"?