Complex sentence: Sixteen harbour defence motor launches purchased in the United States were commissioned between March 1943 and March 1944 and operated as the 124th and 125th Motor Launch Flotillas, based on Auckland and Wellington respectively.
Split into simpler sentences: Sixteen Harbour Defence Motor Launches (HDMLs) purchased in the United States were commissioned between March 1943 and March 1944. They operated as the 124th and 125th Motor Launch Flotillas, based on Auckland and Wellington respectively.