5. Communications. The distances are so great that maintenance (except in locally obtained food and fuel) of forces operating against Caucasia would be a difficult problem, particularly having regard to the need to convert the railway gauge. If the Caucasus Mountains are reached there are only three means of entry into Trans-Caucasia. Along the Black Sea coast the mountains run precipitously into the sea. The railway still has a fifty mile gap in spite of many years work, and the road is cut into the mountain side and its complete destruction by the Russians would be simple.