The army of Ala -ud -din Khilji was recruited, equipped, trained and paid by the center. The army minister directly recruited the soldiers of the sultan's army. The soldiers were supplied with horses, arms etc. by the state and were paid in cash by the royal treasury. The soldier with one horse was paid two hundred thirty four Tankas for a year while a soldier with two horses was paid seventy eight Tankas more. The sultan's army consisted of 4, 75,000 cavalrymen. War elephants also constituted an important part of the army. Swords, bows and arrows, mace, battle axe, dagger were important arms used by the soldiers. Stone-throwing machines were also used in wars.
Ala -ud -din Khilji's army was based on the Turkish model and divisions of unit units rested on the decimal system. Ala -ud -din also took measures to stop the corrupt practices by the soldiers which were reducing the effective strength of the army. He instituted the practice of recording the huliya (descriptive roll) of individual soldiers and that of Dagh (branding of horses). The Diwan - i -Arz kept the record of all of them. Besides a strict review of the army was occasionally made and horses and arms of soldiers were thoroughly examined.
Ala -ud -din repaired the forts constructed by Sultan Balban on the north-west frontiers. He also constructed new forts there and other places also like Kampil, Patiali and Bhojpur. Soldiers were permanently in these forts and arrangements were made for regular supply of arms to them. Grain and fodder always remained stored in these forts. Thus, all forts were always kept prepared for all eventualities in case of any invasion.
During his reign, larger part of northern India was conquered, all rulers of south India were defeated and all Mongol invasions were successfully repulsed. This proves that had Ala -ud -din Khilji succeeded in building up a strong army.