Following their defeat at the gates of Vienna in 1688, the Ottoman Empire went into a long decline and Russia and Austria nipped away at its European lands. Many of its subject provinces started to agitate for more independence as Ottoman power waned, and in quite a few there was open revolt, though the typical outcome was the Ottoman Empire came to terms with them, albeit usually leaving them virtually independent. This is the story of one of those states, the (alternative) history of New Byzantium.
In 1716, Prince Eugene of Savoy defeated the Turks at Petrovaradin. The Banat and its capital Timişoara was conquered in October 1716. The following year, after the Austrians captured Belgrade, the Turks wanted peace and in 1718 the Treaty of Passarowitz was signed. The Austrians maintained control over Belgrade, leaving the Turks with control over the south bank of the Danube river. By the outbreak of the Russo-Turkish war in 1735, Russia had managed to secure a favorable international situation by signing a few treaties with Persia in 1732–1735 (which was at war with Turkey in 1730–1736). Austria had been Russia's ally since 1726.
Emboldened by this, many of the remaining territories of what is now New Byzantium felt it was time to remove the Turkish yoke and rose in revolt. In the absence of their Sanjak (Governor) the population of Salanik (Thassaloniki) overthrew the remaining Ottoman garrison and established New Byzantium. The Turkish army, busy fighting Russia and Austria, was not in a position to put down the revolts and the revolutionaries. Russia and Austria could see the benefit of such a revolt in the Turkish rear, fed the revolutionaries with money and surreptitious military assistance. At the end of the war, the Turks attempted to restore order but were too weak and the revolutionaries, with the help of Russian forces landed from the Black Sea and Austrian Grenz troops, forced Turkey (through gritted teeth) to give them semi-independence at the Treaty of Edirne
Under Austrian and Russian influence (and to stop the factional fights that threatened to tear the new Byzantium apart - or even worse, become that most dangerous of things, a Democratic republic), a new king, or Basileios, with vague connections to the last Byzantine emperors was found and installed as Constantine X, and the Greek Orthodox church was quick to move an autocephalous Patriarch to the new capital of Byzantion. During the 1740 - 1748 War of Austrian Succession, New Byzantium happily took Prussian and French money to attack Austria, but spent most of this loot in building up its own army, and its attacks on Austria were slow and largely ineffective. When the French and Prussians pressed this point, Constantine X responded that he needed more materiel and training to build a "proper" army - which France duly gave, and is reflected in the French flavour of the army even today.
By 1751, Turkey felt Austria and Russia were sufficiently weakened to try and overturn the treaty of Edirne and attacked New Byzantium, and at this point it became clear that Constantine's policy in the War of Austrian Succession had been to build his own forces up while expending as little energy as possible in actually fighting Austria, and the French trained Byzantine army, supplemented with its European mercenary soldiers demobbed from the recent wars (and urgently recruited as mercenaries) gave the still largely feudal Turkish army a bloody enough nose in a series of engagements that made the Turks rethink their policy towards this irritating but relatively small new demistate. The Treaty was re-ratified, but no-one was under any illusion that this was a stable situation.
The troops of the revolt were primarily men serving in the Turkish army as well as a ployglot collection of mountain men, farmers and city militias. They were joined by a ragtag collection of demobbed European soldiers, idealists and ne-er do wells who formed the core of Western style cavalry and infantry units, but without Russian and Austrian help the revolt would probably still have been put down.
After being anointed, Constantine quickly realised that his best option was to build a core force of European style heavy cavalary and line infantry which the Turks had no real answer to, but use it in conjunction with the local troops who were better at the light infantry and light cavalry warfare that Turkish forces excelled in. With a vengeful Ottoman empire breathing down his neck he know there was no time to train his own troops, so like the Byzantine emperors of old he used the French and Prussian money to recruit more European soldiers as mercenaries. He resurrected the names of some of the great regiments of the Byzantine Empire to add lustre to loot.
In addition he regularised the local ex-Ottoman light troops, as he and his French advisors (None other than Marshhal de Saxe was chief advisor, and in fact it is his influence that drove the formation the armoured Scholae lancers, but that is a story for another time....) realised that Balkan light troops, properly armed and with some discipline, were the match of any (indeed most European armies were busy recruiting them as well). The desultory border fighting with Austria was more about training this new army to operate together, and capturing equipment, before the inevitable clash with Turkey. This was accomplished in the nick of time, so that when the Turks attacked in 1750 the locals, stiffened by the mercenaries of the new Varangian Guard, Foreign Legion, Latinikon, Gianitzaroi, Turkopoloi and their own light troops were able to inflict enough early reverses on them to delay their plans. At the same time, fortuitously, many demobbed Prussians, French, Austrians and other nationalities were available after the ending of the War of Austrian Succession and more were hastily recruited as mercenaries and put into new battalions and squadrons, and it was this force that then caused the Turks sufficient damage to persuade them too sue for peace till another day, and the Truce of Edirne was signed in 1751.
Roll forward to today, and the early stages of the Seven Years War. New Byzantium is (as usual) carrying out a delicate balancing act of trying to get money out of warring European states and collaborating with Turkey to extract trade revenue while carefully watching them as well. Austria and Russia are fighting with France against Prussia and England, and the new Basileos, Alexius VI is busy negotiating with the British for payments to attack Austria and Russia, and letting them use his main port as a naval base in return. The newly resurrected emblem of the Byzantine Eagle is truly watching both ways (or is truly two-faced, as its opponents claim)