Why Peacekeepers of Sol no longer uses the name Marines

What happened to the British Marines in Peacekeepers of Sol?

The fictional setting replaces Marine terminology because colonial Marine forces committed atrocities that tainted the name.

This explanation concerns the fictional history of Peacekeepers of Sol. In that setting, US colonial Marine forces commit atrocities during an earlier human war in space. The resulting stigma attaches to the Marine name, including units with different traditions, and helps produce a renamed combined ground force. The fictional war is discussed as an example of prolonged fighting leading people to stop recognizing others as human.