One note of interest was the poor reliability of the German tanks such as the Panther and Tiger; constant mechanical failures meant that German tank divisions were rarely able to field a full complement of tanks and were often diminished below 50% combat readiness. The book The Last Battle by Cornelius Ryan makes mention of the 7 million foreign workers who were forcibly brought into Germany to work in the factories and businesses --- many of them in military assembly lines. Ryan specifically writes about these foreign workers in German tank manufacturing, who sabotaged every part they could[2] and may have contributed to the rate of breakdown of German tanks in the field.