The siege of Buda took place at Buda castle (called Festung Ofen in German), part of the twin capital cities of the Kingdom of Hungary. The Hungarian revolutionary army was led by General Artúr Görgei during the Hungarian War of Independence. Part of the Spring Campaign, the siege began on 4 May 1849, ending with the Hungarian capture of the castle by assault on 21 May.
Buda Castle was the only fortress throughout the entire war to be taken by storm by the besiegers on either side. All other fortresses capitulated following agreements between besiegers and besieged. The siege of Buda was also the shortest siege of the war (18 days). The senseless bombardment of Pest by Austrian commander Major General Heinrich Hentzi caused destruction of classic buildings on the shores of the Danube. Other regions of the capitals also suffered heavy damage due to the artillery duels between the two sides.
The capture of Buda Castle completed the liberation of the Hungarian capital cities (Buda and Pest). Thanks to this, the second Hungarian revolutionary Government, led by Bertalan Szemere together with Governor-President Lajos Kossuth, returned from Debrecen, the interim capital of the Hungarian revolution, to the capital of Hungary.
On 21 May 1849, the same day as the capture of Buda, the two emperors Franz Joseph I of Austria and Tsar Nicholas I of Russia signed the final treaty in Warsaw, which agreed on the intervention in Hungary of 200,000 Russian soldiers (and an 80,000-strong reserve force, if necessary), in order to help the Austrian Empire crush the Hungarian revolution.
Towards Vienna or to Buda?
Following the relief of Komárom from the imperial siege and the retreat of the Habsburg forces to the Hungarian border, the Hungarian army had two choices as to where to continue its advance. One was to march on Pozsony and Vienna, in order to force the enemy to fight on their own ground; the other was to return eastwards to retake Buda Castle, which was held by a strong imperial garrison of 5,000 men under the command of Heinrich Hentzi.
The first choice was supported mainly by the chief of the general staff, Lieutenant-Colonel József Bayer, and initially by Görgei; the second option's main proponent was General György Klapka, commanding I Corps. The main reason for the first plan as supported initially by Görgei was the threat of Russian intervention. The Hungarian commander thought that his army had more chance of success if it could destroy the Austrian imperial army before the Tzar's troops arrived.
However, Görgei was quickly convinced by those who wanted to liberate the castle of Buda first. So he changed his mind and supported the second choice. Although the first option seemed very attractive to him, its success was nearly impossible. While the Hungarian army gathered before Komárom had fewer than 27,000 men, the imperial army awaiting them around Pozsony and Vienna had 75,633, of which its effective combat strength was 54,443 with 237 guns, so it was twice the size of Görgei's force. Furthermore, the Hungarian army was short of ammunition.
Capturing Buda Castle seemed more achievable at that moment, Klapka arguing that it was not suited to withstand a siege, and could be taken quickly by a surprise attack, which could be achieved with the available Hungarian forces. Leaving a strong imperial garrison in the middle of the country would represent a major threat if the main Hungarian army wanted to move towards Vienna. Because attacks from the castle could cut the Hungarian lines of communication, it would need to be blockaded by a significant force in order to prevent such sorties. The fact that the only permanent bridge on the Hungarian part of the Danube (temporary pontoon bridges existed in many places), the Chain Bridge, was under the control of the imperial garrison in Buda Castle made it impossible to transport supplies to the Hungarian armies fighting in the West. Thus, the castle's real strategical importance underlined the need to take it as soon as possible.
Furthermore, the presence of Josip Jelačić's corps in southern Hungary led the Hungarian commanders to believe that the Croatian ban could advance towards Buda at any moment to relieve it, cutting Hungary in two. The Hungarian staff understood that without taking the castle, the main army could not campaign towards Vienna without putting the country in grave danger and that at that moment it was impossible to achieve victory against the numerically and technologically superior imperials gathered on the Western border of Hungary. This indicates that the arguments of those historians who wrote that Görgei made a mistake by not continuing the attack towards Vienna, because he had a great chance to take the Austrian capital and win the war before the Russian intervention, are wrong, and at that moment (before the arrival of the Hungarian reinforcements from the south) the only place which could gain a victory was the Castle of Buda.
Beside the military arguments in favour of the siege of Buda, there were political ones too. After the declaration of the independence of Hungary, the Hungarian parliament wanted to persuade foreign states to acknowledge Hungary's independence and knew that there was more chance of achieving this after the total liberation of their capital city Buda-Pest. And the capital city also included the Buda castle. So the council of war held on 29 April 1849 decided to besiege and take Buda Castle, and then, after the arrival of reinforcements from southern Hungary, move to attack Vienna in order to force the empire to sue for peace and recognize the independence of Hungary.
The castle before the siege
The Turkish occupation of Buda had ended on 2 September 1686, after a bloody siege by the Austrians. After that, the castle was the property of the Hungarian king (who was at the same time Holy Roman Emperor until 1804, and after that Austrian Emperor), and was defended by foreign (not Hungarian) soldiers led by a foreign officer. After the Hungarian revolution succeeded and the Batthyány Government was formed, the castle was still defended by foreign soldiers who had to recognize the Hungarian Government's authority. Because he did not want to do so, the commander of the garrison, Lieutenant General Karl Kress resigned and left on 11 May 1848. So, too, did those foreign units stationed in the castle who were against the Hungarian revolution, such as the Italian 23rd infantry regiment, who clashed with the newly conscripted Hungarian soldiers on 11 June 1848, resulting in many deaths. After this conflict, on the orders of the Hungarian War Ministry, the Italian 23rd infantry regiment was withdrawn from Hungary.
Following the imperial campaign against Hungary that began in mid-December 1848 and was led by Field Marshal Alfred I, Prince of Windisch-Grätz, the ensuing retreat of the Hungarian armies, and the Hungarian defeat at the Battle of Mór, the Habsburg troops entered the Hungarian capitals on 5 January 1849. The free Hungarian parliament, the National Defense Committee (interim government of Hungary), and a long convoy of civilians with all their possessions fled through the cold and snowy winter east to the Tisza River, installing the interim capital at Debrecen. The first thing Windisch-Grätz ordered after entering Buda was the occupation of the castle and the Gellért Hill. Windisch-Grätz named Lieutenant General Ladislas Wrbna as the commander of the Buda Military District, the military commander of the imperial troops in the capitals. But at the end of February, when the commander-in-chief prepared to attack the Hungarian army, he took Wrbna with him on the campaign, leaving Major General Heinrich Hentzi, commander of the imperial garrison of the Castle of Buda, to take overall command of the troops in Buda and Pest.
During April 1849, the main imperial force led by Field Marshal Windisch-Grätz suffered one defeat after another and retreated towards the western border of Hungary. The Hungarian victory at Nagysalló on 19 April had decisive results for the imperial occupation forces stationed in Hungary. It opened the way towards Komárom, bringing its relief to within just a couple of days' march. At the same time it put the imperials in the situation of being incapable of stretching their troops across the very large front which this Hungarian victory created; so, instead of concentrating their troops around Pest and Buda as they had planned, Feldzeugmeister Ludwig von Welden, Windisch-Grätz's replacement as the imperial commander-in-chief in Hungary, had to order the retreat from Pest to avoid being caught between the Hungarian pincers.
When he learned of the defeat at Nagysalló on the morning of 20 April, he wrote to Lieutenant General Balthasar Simunich, the commander of the force besieging Komárom, and to Prince Felix of Schwarzenberg, the Minister-President of the Austrian Empire, that in order to secure Vienna and Pozsony from Hungarian attack he was forced to retreat from Pest and even from Komárom. He also wrote that the morale of the imperial troops was very low, and because of this they could not fight another battle for a while without suffering another defeat. So, the next day he ordered the evacuation of Pest, leaving an important garrison in the fortress of Buda to defend it against Hungarian attack. He ordered Jelačić to remain in Pest for a while, and then to retreat towards Eszék, in Bácska, where the Serbian insurgents allied with the Austrians were in a grave situation after the victories of the Hungarian armies led by Mór Perczel and Józef Bem.
On 24 April, the last imperial soldiers left Pest. That same morning at 7 o'clock seven, hussars from the Hungarian II Corps entered the city, welcomed by the cheers of happy crowds of citizens who had been waiting so long to be liberated. In Buda the next day, Hentzi convened two meetings with his officers and declared that he would defend the Castle of Buda until his last breath.
Preparations for the defence of Buda
The Castle of Buda—or, as it is also known, the Upper Town of Buda (budai felsőváros)—lies on a hill 167 metres (548 ft) above sea level and 70 metres (230 ft) above the Danube which flows beneath it. This so-called Castle Hill (Várhegy) has the oblong irregular shape with its tip to the southeast and its base to the northwest, with a length of 660 metres (2,170 ft). On its wider, northeast side with the Royal Palace is 156 metres (512 ft) high, while its southwest side is 163 metres (535 ft) high. The hill is surrounded by suburbs, with the Danube to the east 260-meter-wide (850 ft), Gellért Hill to the south 235-meter-high (771 ft), Naphegy 158-meter-high (518 ft) and Little Gellért Hill (Kis-Gellérthegy) 168-meter-high (551 ft) to the southwest, Kissváb Hill (Kissvábhegy) 249-meter-high (817 ft) to the west, and Rókus Hill (Rókushegy or Rézmál) 249-meter-high (817 ft) to the northwest; also to the northwest are Ferenc Hill (Ferenchegy or Vérhalom) 265-meter-high (869 ft) and Kálvária Hill (Kálvária-hegy) 161-meter-high (528 ft), and József Hill (Józsefhegy or Szemlőhegy) 232-meter-high (761 ft) and Rózsa Hill (Rózsadomb) 195-meter-high (640 ft) to the north. Across the Danube to the east there are no heights near the castle.
The heights of the walls surrounding the castle were not uniform. They were punctuated by old circular bastions, called rondellas, and newer, polygonal bastions, close enough together to enable them to bring fire to bear on the enemy attacking the walls between them. The fact that there were no moats, beneath the walls, and that the hill was surrounded by houses and gardens except near the four castle gates, made the besiegers' job easier. The castle's defenses were of 16th century standard, because fortification modernization of later periods had almost no effect on this castle without exterior walls and defenses and consisting only of a "core fort". The most important defenses of the castle were its walls surrounding the edges of the Castle Hill. This wall was built in different periods and was repaired in various ways in the 163 years between the sieges of 1686 and 1849. Because of this, it was of different widths, without embrasures, protective structures, etc., and lacking the most basic elements of modern siege technology. The gates were mostly vestiges of the past rather than real castle gates, lacking trenches or drawbridges. Comparing it with Hungarian castles such as Arad, Temesvár, Komárom, Gyulafehérvár, Pétervárad or Eszék, it can be said that it was centuries behind these; and because of this the intention to defend it came as a surprise to many. But the imperials understood the importance of holding the Castle of Buda as long as they could, both for political and symbolic reasons as well because of having accumulated a large store of military equipment there; and they did not want to give all of these up so easily.