In nineteenth century colonial Algeria, railways were a necessary condition for the expansion of colonisation and for the economic development of this most important French colony. Railways were both political and military instruments as well as important to the development of trade and in the attraction and settlement of colonists. When they were constructed in Algeria, railways became passage ways for streams of settlers and bulky goods which it had hitherto been impossible to transport by land in quantity. Moreover, the development of commercial agriculture was made possible only after the construction of the first lines and the subsequent reduction of transportation charges. The fertile plains and the main ports of Algeria became targets for railway planners who were anxious to increase the volume of exports towards the Metropole. The impact of railways on agricultural patterns in terms of means of production and output was also significant. The development of colonial agriculture was in part a consequence of the influence of rail transport. Furthermore, railways had important effects on the availability of resources and the economic accessibility of various parts of the colony. The mineral areas of Algeria were opened by the railways which,due to their capacity to move raw materials in mass, provided a valuable stimulus to industrial development in France and in Europe. Railways had, in addition, widened the colonial market for French manufactured products after the 1880's, thereby monopolising the distribution of the growing volume of industrial goods from France and other European countries. Colonial railways were the main target for Metropolitan investments in the period 1858-1892. In addition to providing investors with substantial dividends and various advantages, they also represented important markets for French and European industries. iii However, despite their economic and strategic significance, railways in Algeria were undeniably a heavy financial burden on the state because of the Garantie d'interet system. This aroused a lot of concern and a political outcry which led to the end of the railway development in the nineteenth century. Above all, the railways proved, in times of armed Algerian resistance, the best means for the mass movement of troops and military equipment. Thus railways constituted the tool by which military occupation was achieved and settlement policy advanced. In time of relative peace they proved the most efficient factor behind the attraction of colons, the economic subjugation of the Algerians and the global development of the colony.