[2][3][4][5][6][7][8][9][10][excessive citations] In exchange for land-grants, religious freedom and favorable tax rates, they colonized the area and served as the bulwark for the monarchy against Ottoman incursions.

Germans had been recruited by Hungary in the late 18th century to resettle and develop the Danube River Valley, and became known as Donauschwaben.

The military regiments formed by the settlers had a vested reason to stand and fight and were familiar with local terrain and conditions.

The Ottoman wars in Europe caused the border of the Kingdom of Hungary – and subsequently that of the Habsburg monarchy – to shift towards the northwest.

In 1435, in an attempt to strengthen the defences against the Ottomans and Venice, King Sigismund founded the so-called tabor, a military encampment, each in Croatia, Slavonia and Usora.

The Habsburgs aimed at holding the Ottoman forces on Hungarian and Croatian territory before they could reach Austria, but did not have a clear defense plan.

During the 16th and 17th centuries, the military administration of the Frontier was moved away from the Croatian ban and the Sabor (Parliament) and instead instated in the high command of Archduke Charles and the War Council in Graz.

Eventually, the whole male population of the Military Frontier became professional soldiers who served the Empire on several fronts and through many European wars, even after the relaxation of the Ottoman threat.

[22] The area was settled primarily with Croatian, Serbian and German colonists (known as grenzer and graničari) who, in return for land grants, served in the military units defending the empire against Ottomans.

[23] The large community of Serbs concentrated in Banat, southern Hungary, and the Military Frontier included merchants and craftsmen in the cities, but mainly refugees who were peasants.

After the Ottoman army was repelled at the Battle of Vienna in 1683, the Great Turkish War ended with much of the former Croatian lands under Habsburg control.

Despite this, the Frontier system was retained, and expanded onto former Ottoman territories in Lika, Kordun, Banija, lower Slavonia, Syrmia, Bačka, Banat, Pomorišje, and Transylvania.

The Habsburg Empire valued the ability to centrally control the area and to draft cheap and numerous army units.

Over the following century, each regiment had one section of Seressaners that organized border patrols towards Bosnia, particularly on difficult terrain, and stopped incursions of bandits.

[24] When in 1699 and 1718 the lands of Croatia and Hungary returned, which was previously occupied by the Ottomans, the vast majority of that area became the Military Frontier.

Throughout the entire region of this frontier various ethnic groups were settled including Croats, Serbs, Albanians and others which were also all together called Vlachs.

[27][28][29] The Serbian Free Corps of 5,000 soldiers had been established in Banat, composed of refugees who had fled earlier conflicts in the Ottoman Empire.

Austrian forces occupied Serbia, and many Serbs fought in the Habsburg free corps, gaining organizational and military skills.

[32] By 1791, however, the Austrians were forced into withdrawal across the Danube and Sava rivers, joined by thousands of Serb families who feared Ottoman persecution.

By the end of the 18th century, it had already become apparent for some time that the Ottomans were on the decline and were not likely to attempt any further invasions north of the Sava River.

Although he did not have the power to abolish it, he secured approval for reforms and in 1848 the Military Frontier sent representatives to the Croatian Sabor,[33] however, this was revoked in the 1850s.

In order to attract Serbs into Hungary, emperor Leopold I decreed that they would be allowed to elect their own ruler, or Vojvoda, from which the name Vojvodina derives.

Later the Habsburgs did not allow Serbs to elect their own vojvoda; they incorporated the region into the military frontiers of eastern Slavonia and the Banat.