Ottoman Empire
History
Military Structure
The core of the Ottoman military were the Janissaries.
Administrative Structure
In the early era, the empire was divided into eyalets (ایالت, literally "states") led by beylerbeys (بكلربكی, literally "bey of beys"). Sometimes they were called beylerbeyliks instead. Note that pasha (alternatively basha, پاشا) was a military honor rather than an administrative title, but pasha who also were beylerbeys sometimes referred to their realms as pashaliks.
Eyalets were subdivided into sanjak (سنجاق, literally "flag") led by sanjak-beys (alternatively sanjaq- or -beg, سنجاق بك).
Conquered nations were forced to convert to Islam, subjected to serfdom, and pay their sons to the Janissaries.
Following the Tanzimat reforms, the empire was redivided into vilayets (ولایت, literally "province") led by vali (from the title wāli (والي) used in the wider Islamic sphere). The Millet system also emerged, which granted a degree of freedom of religion.
Eyalet of Rumelia
The most powerful eyalet was Rumelia, encompassing all European lands of the empire. (Essentially the Balkans.) Until the capture of Constantinople, Adrianople served as the capital of both Rumelia and the empire.
This eyalet was reorganized into the vilayet of Salonica in 1867.