Having adequate supplies was a constant problem for the Greek Army. Although it was not lacking in men, courage or enthusiasm, it was soon lacking in nearly everything else. Due to her poor economy, Greece could not sustain long-term mobilisation. According to a British report from May 1922, 60,000 Anatolian native Greeks, Armenians and Circassians served under arms in the Greek occupation (of this number, 6,000–10,000 were Circassians). In comparison, the Turks had also difficulties to find enough fit men, as a result of 1.5 million military casualties during World War I. Very soon, the Greek Army exceeded the limits of its logistical structure and had no way of retaining such a large territory under constant attack by initially irregular and later regular Turkish troops. The idea that such large force could sustain offensive by mainly "living off the land" proved wrong. Although the Greek Army had to retain a large territory after September 1921, the Greek Army was more motorized than the Turkish Army. The Greek Army had in addition to 63,000 animals for transportation, 4,036 trucks and 1,776 automobiles/ambulances,(according to the Greek Army History Directorate total number of trucks, including ambulances, was 2500. Only 840 of them have been used for the advance to Angora, also 1.600 camels and a great number of ox and horse carts, whereas the Turkish Army relied on transportation with animals. They had 67,000 animals (of whom were used as: 3,141 horse carts, 1,970 ox carts, 2,318 tumbrels and 71 phaetons), but only 198 trucks and 33 automobiles/ambulances.