The D4 (D'ama) class light cruiser was a type of warship designed and built by the Klingon Empire during the mid 22nd through mid 23rd centuries. (TOS novel: The Final Reflection) A vessel of this type was encountered and destroyed by Captain Garth in October of 2250, in what became known as the first Battle of Axanar, before a formal declaration of war had been made by the Klingons. Thus, this event pre-dated the Four Years War. (Star Trek: The Four Years War)