and West Africa, which were notoriously unhealthy for European troops until the early 20th century. "Native" troops were usually recruited from tribal or other groups that had long-established martial traditions. It was not uncommon for colonial armies to favour the races that had shown the fiercest opposition to the initial conquest of a given territory (examples being the Sikhs of India and the Rif tribesmen of Morocco). Colonial units could be employed in campaigns or conditions in which the use of conscripts from metropolitan regiments would be politically unpopular. Also, the use of local troops often made the actual colonization more palatable for the locals. Colonial troops could be used to garrison or subdue other territories than those in which they were recruited to avoid problems of conflicting loyalties. For example, Italy used Eritrean askaris in Libya and during both wars with Ethiopia (1895 and 1936). Indian regiments garrisoned Aden, Singapore and Hong Kong at various times in the 19th and the early 20th centuries. In the 1950s, the Portuguese used African troops from Mozambique to garrison Goa, and the Dutch had West Africans (Zwarte Hollanders) for service in the East Indies during much of the 19th century. Disadvantages Colonial troops were usually more lightly equipped than their metropolitan counterparts, which were usually given priority in issuing new weaponry. That arose primarily from the predominant roles of light infantry or cavalry of colonial forces, which were designed for low intensity warfare against poorly-armed opponents in difficult country. Until the Second World War, artillery or mechanised units rarely had indigenous troops although the Italian colonial army maintained a number of Eritrean, Somali and Libyan mule artillery batteries, and there were locally-recruited mountain batteries in the Indian Army. The relative lack of up-to-date weaponry and training put colonial troops at an initial disadvantage when they faced modern opponents such as the German or Japanese armies of the Second World War. Even earlier, the African and Indian troops that had been sent to France in 1914 encountered a climate, diet and general conditions of service greatly different from those with which they were familiar. The Senegalese tirailleurs of the French Army had to be withdrawn to southern France for recuperation and training during the harsh winters of the Western Front. All Indian troops, with the exception of some cavalry regiments, were withdrawn from the Western Front in October 1915, to serve in Mesopotamia,