Map 1

Contemporary chroniclers have described what ensued with some detail. Timur had fortified his position with dikes and ramparts. There is consensus among historians that Timur's forces cut the water supply  to Bayazed's army and that Bayazed lost the Battle of Ankara because of the thirst of his troops. It is worthwhile to mention that at large armies need reliable and abundant water supplies more than anything else. Foot soldiers were involved in hand to hand combat and cavalry needed water for the horsemen and the horses during the battle, which lasted a whole day in the heat of July. It was arid country, and water was the lifeline of the old armies as the petrol is for modern armies. TOPOGRAPHY, CLIMATE AND HYDROLOGY Cubukcay is the main water course that flows on the Cubuk Plain. Hammer, who is one of the best sources about the Ottoman history, states that it was Cubukcay that Timur diverted. This assumes that Timur's army was upstream and the Ottoman Army was downstream. The question is where the water was diverted. Water will continue to flow unless it is stored somewhere. The base flow of Cubuk Creek is only a few hundreds liters per second. To store this flow for one day one needs a storage less than 50,000 cubic meters. If the depth of storage is one meter the area of such a reservoir would be 50,000 square meters, about one twentieth of a square kilometer. Thus the storage requirement for one day is not very large. There are two basic methods of storing the water of a water course. Usually a dam is built in a narrow reach of the valley immediately downstream of a good reservoir site. Another method, less common, is to store water in a tributary with a good reservoir site and divert the flow of the main water course with a diversion dam and a canal. Such reservoirs are called off stream reservoirs. It happens that there is a tributary on the Cubuk valley which is eminently suitable for such a scheme (It was considered as an alternative during the water supply investigations of the City of Ankara in early sixties) . This tributary is immediately downstream of the Town of Cubuk on the right bank of the Cubuk Creek. The reservoir area is very flat and a low dike  a few hundred meters long could easily store the daily flow volume of the Cubuk Creek. It is the only site in the Cubuk Valley where large amounts of water can be stored with minimum amount of earthwork. Timur and his engineers should have immediately seen this opportunity to divert the flow of Cubuk Creek the day of the battle (Map 2). This map also shows the location of structures to carry out the plan of Timur.

 

 
 

Map 2

The climate of Central Anatolia (Asia Minor) is semi-arid. Annual precipitation in Ankara is about 350 mm (eight inches). Daytime temperatures in Ankara during the month of July reach 35 centigrade (95 degrees Fahrenheit) In summer relative humidity is very low, and this increases water loss by perspiration. Shallow wells yield just enough water for domestic use. Such conditions put a high price on water for armies, especially when tens of  thousands men and horses need water. Armies have to move along the water courses to satisfy the thirst of their soldiers and horses (and their elephants). No battle could take place without an abundant supply of water nearby.   STRATEGY Waiting for the impetuous Bayazed and his well trained army, Timur and his engineers discovered the ideal off stream reservoir site on the west of the Cubuk Plain. A diversion dam was built upstream of the tributary which flowed trough the reservoir. Another low dam was built to close the off stream reservoir site. A canal was dug from the diversion dam upstream which would carry water to the off stream reservoir. Such engineering works were made possibly by the availability of thousands of men. In addition Timur had, according to the historians, 32 trained elephants. Historians (see references) state that Timur fortified his position with dikes and palisades before the battle. These were in reality a canal and two low earth dams (one on the Cubuk creek and one on a tributary water course). When Bayazed arrived, he and his commanders probably saw the Cubuk Creek flowing. But as soon as the battle started the gap in the diversion dam was closed. Water was diverted to the canal and ultimately to the off stream reservoir.

Phase 1: The Trap. Timur is waiting for Bayazed. Timur has partially built a diversion dam upstream with a breach to let the creek continue flowing downstream. Another low dam is built on a western tributary downstream which has a large storage capacity . A canal starting from the diversion dam toward this low dam is constructed to divert water during the second phase. When Bayazed arrives he sees the Cubuk Creek flowing.

Phase 2: The Cubuk creek downstream was now dry and there was  no other source of water for the Ottoman Army. The battle lasted one full day, in the heat of July and the Ottoman Army was exhausted and thirsty. The opening at the middle of the diversion dam is closed. Water starts to flow into the canal filling slowly the the reservoir side downstream. Cubuk Creek ceases to flow starting upstream. Ottoman and Mongol Armies are engaged in combat.

Phase 3: Cubuk Creek is completely dry downstream. Through the day long battle in the heat, Bayazed's well trained  army is without water, one of the reasons given by historians for Bayazed having lost the Battle of Ankara.