The history of military of the Ottoman Empire can be divided in five main periods. The foundation era covers the years between 1300 (Byzantine expedition) and 1453 (Fall of Constantinople), the classical period covers the years between 1451 (enthronement of Sultan Mehmed II) and 1606 (Peace of Zsitvatorok), the reformation period covers the years between 1606 and 1826 (Vaka-i Hayriye), the modernisation period covers the years between 1826 and 1858 and decline period covers the years between 1861 (enthronement of Sultan Abdülaziz) and 1918 (Armistice of Mudros). - Source: Wikipedia