Management of the Army
Muslims, from the very beginning, had knowledge of managing the army. In Islamic army there would be front detachment, back detachment, right detachment, left detachment and middle detachment. The commander would be in the middle of the army so that he could watch the whole army. From there he guided the army in all the circumstances.
Umar bin al-Khattab (Radhi Allahu Anhu) had built an office especially for the army. It would enroll the soldiers and manage their payments. He kept them away from business, farming and industry so that they could be devoted to the victories of Islam. For comfort of the soldiers he built forts, camps and cantonments. For this very purpose he had new cities built like Fustat in Egypt and Kufa and Basra in Iraq. It was during his age that the system of Murabata (staying along with the borders of the enemies with soldiers and horses) was introduced, and this arrangement was made especially in the coastal areas such as Alexandria so that invasions upon Muslims’ coastal areas could be prevented.
During the caliphate of the Umayyad, Muslims came to know the system of invasions in winter and in summer. These invasions are those which were carried out against the Byzantine sultanate in winter and in summer so that they might be taught a lesson and they could not even think of attacking coastal areas of Muslims in Syria.
Abbasid era is known for its grace and excellent management. In this era, Muslims soldiers were divided on the basis of their nationalities. To take examples, the archers would be from Arab, the walking detachment from Persia and especially from Khurasan. In the early age of Caliph Mu’tasim (218-228 AH) the Turk became a part of Islamic army boosting its number. Muslims were not negligent from the navy, too. Rather, they paid much attention to it and fought fierce battles through it. In the caliphate of Uthman bin Affan (Radhi Allahu Anhu) the famous naval battle Zat-us-Sawari was fought. In it, Muslims defeated the Roman fleet in the Mediterranean Sea. Muslims paid so much attention to naval battles that in 54 AH they founded a ship manufacturing factory in Rauda Island of Egypt which played an important role in Islamic navy.
While selecting skilled commanders, Muslims always considered bravery, intelligence, cleverness, personal strength, excellent planning and obedience for the religion etc. Here are the names of some famous Muslim commanders: Khalid bin Waleed, Amr bin al-Aas, Sa’d bin Abi Waqqas, Abu Ubaida bin Jarrah, Uqbah bin Nafe, Musa bin Nusair, Tariq bin Ziyad etc. These are the ones who were crucial for spreading Islam everywhere.