At the end of WW2, the Nazis were attempting to produce a full sized battle rifle. After much infighting by German high command, the STG44 (Sturmgewehr 44) or "Storm Rifle Model 1944" was adopted in April of '44. It was a universally respected battle rifle, and could have changed the war, had it been released earlier.
At the end of WW2, with the collapse of Nazi Germany, the STG's designer Dr. Vorgrimmler, fled Germany to Spain. Francos Spanish govt existed in no small part to German supplying of arms during the Spanish Civil war. Dr. Vorgrimmler and a few assistants began work on what became known as "Centro de Estudios Tecnicos y Materiales Especiales" or CETME. This arms factory produced the CETME Modelo A, the first in a long line modifications and refinements to a basic design. This was the primary battle rifle for many countries well into the 1990's. This weapon gave birth to the Heckler und Koch G3, MP5, G36 and influenced design on many others.