Siege of Khartoum support of the Mahdi, and cut the Egyptian traffic on the Nile and the telegraph to Cairo. Communications were not entirely cut, as runners could still get through, but the siege had begun and Khartoum could only rely on its own food stores, which could last five or six months. On 16 March an abortive sortie from Khartoum was launched, which led to the death of 200 Egyptian troops as the combined forces besieging Khartoum grew to over 30,000 men. Through the months of April, May, June, and July, Gordon and the garrison dealt with being cut off as food
Khartoum main Nile ("see map, upper right") as it zigzags through northern Sudan into Egypt at Lake Nasser. Khartoum is relatively flat, at elevation , as the Nile flows northeast past Omdurman to Shendi, at elevation about away. Under Köppen's climate classification system, Khartoum features a hot arid climate, with only the summer months seeing noticeable precipitation. The city averages a little over of precipitation per year. Based on annual mean temperatures, the city is one of the hottest major cities in the world. Temperatures routinely exceed in mid-summer. Its average annual high temperature is , with six months of the