This article tries to assess the defensive potential of the German South-West Africa and German East Africa on the eve of World War I. The geographical position of each colony, the terrain, the river network, natural borders and climate are treated as key factors in the planning and carrying out of military operations. The discussion also takes note of the various assets which were installed by the colonial power, ie. roads (transport routes), telephone lines and radio transmitters (telecommunication). Special attention is paid to various aspects of the military amassed in each colony, ie. number of troops, levels of combat training, equipment, food supplies, reinforcements (including the possibility of drawing African recruits). Next, the article looks at the general strategy of German defence plans prepared for the eventuality of conflict and the more detailed plans of troop dislocation after mobilization. Both are assessed with regard to the situation and defence requirements of harbours, towns and military installations. The analysis indicates that the preparations and measures undertaken by the Germans proved inadequate in the face of military operations unfolded by the allies.