Strategy and Logistics
These logistical problems were found elsewhere in the Danube valley and across the Hungarian plains (puszta) where temperatures soared in the summer and plummeted below freezing in winter, and hampered all combatants. The surrounding mountains were blocked by snow from the autumn until the spring thaws that swelled the rivers and flooded a third of the plains for much of the year, providing a rich breeding ground for malarial mosquitoes. Hungary lay at the north-west periphery of the Ottomans’ world empire, 1,100km from their European base at Adrianople (Edirne). A field army of 40,000 infantry and 20,000 cavalry required 300 tonnes of bread and fodder a day. Crop yields in eastern Europe were half those of Flanders and other western agricultural regions that could support ten times more non-producers. Even Poland, rapidly becoming the bread basket of western European cities, exported only about 10 per cent of its net crop in the later sixteenth century. It was often impossible to requisition supplies locally in the Danube area, especially as the population tended to be concentrated in isolated pockets, as in Transylvania. The Turks were forced to follow the line of the river during hostilities, reducing their advance to 15km a day. If they set out in April, they could not reach Vienna before July. Not surprisingly, Ottoman armies relied on Belgrade once war broke out, since this was already two-thirds of the way to the front and was the first major city on the Danube west of the Iron Gates (Orsova) pass between the Transylvanian Alps and the northern reaches of the Balkan mountains of modern Bulgaria. These strategic and logistical factors imposed a certain routine on the Turks’ campaigns. Operations began slowly with the collection of troops from across the empire at Adrianople or Belgrade. The main army reached the front in July, leaving only a few months to achieve success before the autumn rains set in during September, while the sultan traditionally suspended campaigns on 30 November with the onset of winter.
Major operations were the exception and most fighting involved cross-border raiding that remained endemic due to political, ideological and social factors. The region lay at the extremity of both the Ottoman empire and the kingdom of Poland, and while physically closer to the heart of Habsburg power, it was still politically distant. All the major powers were forced to rely on local landowners and their private armies who commanded the resources, loyalty and respect of the scattered population. Though wealthy, the magnates in Hungary and Transylvania were adopting expensive new lifestyles, with decorated country houses, foreign university education and grand European tours for sons and heirs. They could not afford large permanent forces to defend the frontier and also needed to satisfy poorer clients who relied on banditry to supplement their incomes from livestock, horse breeding or farming. Those at the centre tolerated the situation as the only way to retain the loyalty of the unruly border lords, and as a convenient means to put pressure on their international opponents. As the secular representatives of opposing world religions, neither the emperor nor the sultan could accept permanent peace without implying recognition of an alternative civilization. The lack of clear frontiers allowed a policy of gradual expansion by encroachment, whereby whichever side was currently stronger exploited weakness in the other to assert the right to collect tribute from border villages. Frontiers shifted back and forth like sand with the tide, while major fortified towns remained immovable rocks that required open war to crack.
Such fortresses began to be built during the 1530s as both the Ottomans and Habsburgs entrenched their hold over Hungary. The Turks had the advantage of shorter interior lines of defence, with a compact position along the middle Danube and in Bosnia to the south-west. They relied on around 65 relatively large castles held by 18,000 regular soldiers, with 22,000 militia recruited from their predominantly Christian subjects to patrol the gaps. The Habsburgs were forced to defend an 850km-long arc to the west and north, partly detached from Austria and Bohemia by chains of mountains. Lateral movement was restricted, since all the rivers drained eastwards into the Ottoman-held Hungarian plain. Each Austrian and Bohemian province had its own militia, but mobilization depended on the Estates who wanted them mainly for local defence. The Ottoman siege of Vienna in 1529 proved a shock and prompted the construction there of new bastioned fortifications in the Italian manner between 1531 and 1567. Plans to modernize these had to be shelved in 1596 due to the peasant unrest and a lack of funds, leaving the capital weakly defended when the Bohemians and Transylvanians attacked in 1619. The civic militia was converted into a regular garrison in 1582, but they numbered only five hundred men.
The Military Frontier
To keep the Turks at bay, the Habsburgs revived and expanded existing Hungarian defence measures to create what became known as the ‘military frontier’. This militarized zone around 50km deep ran the entire length of the frontier and rested on 12 major and around 130 minor fortified posts held by over 22,000 men by the 1570s. Its development and upkeep was heavily subsidized by the Reichstag, which voted eight grants with a nominal value of around 12 million fl. between 1530 and 1582, plus well over another million towards fortress construction. At least four-fifths of this amount was actually paid, despite the confessional tension in the Empire, since the Ottomans were considered a common menace to all Christians.8 Indeed, the largest two grants had been made in 1576 and 1582 at a time when many historians think confessional tension was growing worse. However, disagreements did ensure there was no immediate renewal when the last grant expired in 1587, increasing the dynasty’s dependency on taxes voted by its Estates to maintain particular sectors. Only about half the border troops could be spared from their garrisons, limiting the scope for offensive operations. A major army of 55,000 men was reckoned to cost at least 7.4 million fl. for a single campaign, a figure way in excess of the monarchy’s entire revenue.
Financial considerations forced the Habsburgs to place large sections of the frontier in local hands. The southern or maritime border, based around Senj on the Adriatic, was held by a people known as the Uskoks, after the Serbian for ‘refugee’. This mountainous region could not support the growing number of refugees who were supposed to be paid by the government to defend the frontier with Ottoman Bosnia. Chronic indebtedness forced the Habsburgs to tolerate Uskok raiding and piracy instead. The next sector to the north was the Croatian border around the castle of Karlstadt that had been built in 1579 with funds granted by the Inner Austrian Estates in return for the Pacification of Bruck, and which protected the upper reaches of the Save river, blocking an invasion of Carniola. The Slovenian border around Warasdin on the upper Drava was also subsidized by Inner Austria since it protected Styria. Around half of all the minor posts were concentrated in these two sectors and were manned by colonists settled on crown land in return for militia duty. They received little help from central coffers and were expected to supplement their meagre existence from farming by raiding villages across the frontier.
The Hungarian border was split into three sections, with that in the south stretching from the Drava to the southern end of Lake Balaton and containing the important fortress of Kanizsa. The middle section ran north from Lake Balaton to the Danube, before curving east around the Ottoman salient at Gran where the river makes a right-angled turn from due east to flow south past Buda and Pest. This was the most heavily contested sector, because the Danube valley gave the best access for both sides. The Ottomans were concerned to protect Buda as the seat of their Hungarian government and as a forward base for an attack against Vienna. To forestall this, the Habsburgs built Komorn at the east end of Schütt Island, a large area that stretched west to Pressburg which was formed by two branches of the river and often flooded. Another fortress was constructed at Raab, approximately 40km south west of Komorn, to guard the only practicable route south of Schütt Island into Lower Austria. The lesser fortress of Neuhäusel covered Komorn’s northern flank by blocking the Neutra river. The final Hungarian section stretched eastwards from there to the Tisza river and Transylvania. Its main fortress was Erlau, which blocked the road north over the Matra mountains into Upper Hungary and so safeguarded communications between Austria and Transylvania. Central funds covered only the principal garrisons, leaving the intervening sections in the hands of Hungarian magnates who maintained private armies of haiduk infantry. The haiduks were originally nomadic oxen drovers who had been forced by the partition of Hungary to accept a semi-settled existence as border guards, living in their own villages under elected headmen and relying on banditry between wars to supplement their irregular pay.