Complex sentence: Development work for DPICM projectiles began in the late 1950s, with the first projectile, the 105 mm M444 entering service in 1961, though the submunitions were simple bounding anti-personnel grenades (ICM).
Split into simpler sentences: Development work for DPICM projectiles began in the late 1950s, with the first projectile, the 105 mm M444 entering service in 1961. Its submunitions were simple bounding anti-personnel grenades (ICM).