The M109 is a Self-Propelled Howitzer (SPH) that was developed and produced by BAE Systems. The M109 was introduced in the 1960s to replace the M44.
The M109 Self-Propelled Howitzer (SPH) is the primary mobile artillery unit in NATO and Western countries. Although gradually being replaced with upgraded versions or completely new designs, the M109 continues to soldier on, as it has for over fifty years, with at least 7000 units produced.