Mongols under Kadan’s leadership suffered a major setback at Klis fortress, while hunting king Bela IV. Believing that Bela is in Klis, they surrounded the fortress, launching arrows at it.

However, natural defences of the fortress and its walls combined to make it impervious to such an attack. Thus, Mongols started crawling up the cliffs to the fortress, suffering casualties due to thrown rocks and missiles. Enraged, the attackers managed to reach the walls themselves, engaging the defenders in hand-to-hand combat. Mongols managed to rob the houses located in proximity of the fortress, but failed to take the fortress itself. Realizing the king is not there, Mongols abandoned the attack, riding off towards Trogir and Split.

The text below is the basis of the above account:

“Credentes autem Tatari, quod rex in Clisse presidio consideret, ceperunt undique op#pugnare castrum iacientes sagittas et iacula intorquentes. Sed quia locus erat natura munitus, modicam poterant inferre iacturam. Tunc descendentes de equis ceperunt reptantes manibus ad superiora conscendere. Castrenses vero ingentes lapides revolventes in ipsos aliquot ex eis neci dederunt. Ipsi vero ex casu ferociores effecti usque sub magnas rupes manu ad manum pugnando venerunt diripientes domos predasque non modicas asportantes. Sed cum cognovissent regem ibi non esse, dimise#runt oppugnare castrum et ascensis equis versus Tragurium equitarunt. At Spaletum autem non multi diverterunt ex eis.”

“However, the Tatars believed that the king [of Hungary] was in the fortress of Klis, and so they began to attack the fort from all sides, launching arrows and hurling spears. However, the place was naturally well fortified, and they could cause only limited harm. So then they dismounted from their horses and began to creep up hand over hand to higher ground. But the defenders of the fort hurled huge stones at them and managed to kill a number of them. This setback, however, only made them more ferocious, and they came right up to the great walls and fought hand to hand. They looted the houses and took away no little plunder. But when they learnt that the king was not there, they abandoned their attack on the fortress, and ascending their mounts rode off in the direction of Trogir. All the same, no small number of them turned towards Split.” – History of the Bishops of Split

Reasons for failure to take Klis are manifold. Firstly, Mongols simply lacked time, as they were chasing king Bela. Secondly, they did not have any siege engines with them – at best, they could have had rockets, but even these are not mentioned in the text. They certainly did not have Chinese engineers and infantry with them, nor did they have the resources (and, as mentioned, time) necessary to carry out complex sieges of the kind they did in China. Comparison with a siege of Esztegorm may be illustrative:

Another part of the army turned towards Esztergom, but only a few went that far; they mostly settled some distance away and prepared some thirty siege engines. Those of Esztergom had meanwhile fortified themselves with moats, walls and wooden towers. The innumerable commoners and very rich burghers, knights, nobles, and ladies who gathered in that remarkable fortress were so self-confident that they thought they could resist the whole world. Behold, one day the Tatars surrounded the city, and the prisoners who were with them brought so many bundles of twigs that on one side of the city they all at once built a tall wall of these bundles above the brow of the moat and the thirty siege engines were placed behind that wall. They shot stones at the city and at the wooden towers day and night. This caused such chaos in the city and brought such gloom to the people’s minds that they forgot all about defenses and quarreled among themselves like blind and foolish men. Then, once the Tatars had demolished the wooden towers, they threw with their engines bags full of earth to fill up the moat. None of the Hungarians or the others dared to appear on the brow of the moat because of the stones and arrows. When the Hungarians and the French and Lombards, who were like the lords of the city, realized that they could not hold out, they set fire to the suburb and the wooden houses of which there were many, all the way to the stone palaces. In the houses they burned immense amount of dyed cloth and garments, slaughtered the horses, buried gold and silver, and hid whatsoever goods they had before retiring to the palaces to defend themselves. When the Tatars found out that all by which they wanted to get rich had been burnt, they became very angry and swiftly closed off the city with wooden palisades, so that whoever tried to escape would run into the throat of the sword. Then they started to besiege the palaces. Having taken them swiftly, I believe, to tell the truth, that no more than fifteen people were not killed basely in or outside the city. They inebriated their swords with blood and, in their passion that they had conceived against them, they fried people alive, like pigs.

When they were due to be captured and killed, the better ladies, dressed as beautifully as they could, gathered in one of the palaces and appealed for an audience with the grand prince. All, about three hundred of them, were led out of the city to the prince and asked for the gift of being left alive under his rule. He, however, in his anger for not having won any booty, ordered them to be robbed and beheaded. And that was done right away.

They could not take the citadel of the city, because the Spaniard Simon manfully defended it with his many crossbowmen.

Neither fortress was attacked by siege engines, at least not in a protracted bombardment. In both cases however, Mongols were beaten back.

There is some confusion surrounding the attack on the Klis fortress. Specifically, there is a passage that may imply they had taken the fortress: “This setback, however, only made them more ferocious, and they came right up to the great walls and fought hand to hand. They looted the houses and took away no little plunder. But when they learnt that the king was not there, they abandoned their attack on the fortress, and ascending their mounts rode off in the direction of Trogir.”.

However, sources also make it clear that the fortress had not fallen, as the Mongols had “abandoned attack on the fortress” (“dimiserunt oppugnare castrum“). It is unlikely that an army would have abandoned an attack if fortress was about to fall. The passage also notes that “Ipsi vero ex casu ferociores effecti usque sub magnas rupes manu ad manum pugnando venerunt diripientes domos predasque non modicas asportantes.”. But “magnas rupus” means “great cliffs”, which means that – contrary to the previously provided translation which is generally used in sources – Mongols may not have even reached the walls of the fortress. They reached the cliffs by fighting, implying this might have been a rear-guard action by the defenders, or else that they had reached the gate through a hail of projectiles, only to be dislodged by a sally. If Mongols had been had been climbing the cliffs, then defenders could have launched projectiles from atop the cliffs just as if they were atop the walls. If Mongols were going up the (location of today’s) causeway, then defenders may still have launched stones from the cliffs. There is definitely enough room for there to be houses between the edge of the cliff and the walls of the original fortress, meaning that the sequence of events will have been: 1) Mongols reach the cliffs through fighting (probably only facing an arrow bombardment from defenders atop the cliffs), 2) they climb the cliffs by hands, 3) defenders fight them hand-to-hand as they retreat into the fortress (which itself is situated upon another set of cliffs), 4) Mongols loot the houses outside. This interpretation is supported by the fact that Mongols are nowhere mentioned using ladders or ropes, making climbing of defensive walls rather unlikely.

As explained, fighting happening outside the fortress is far from unlikely, but it is also possible that Mongols may have taken the outer line of walls, assuming these existed at the time. Oprah tower which was the key defensive position of the second line of walls was first mentioned by Pavao III Šubić who died in 1356., so these may or may not have existed in 1241. There were buildings within the second line of walls until they were finally removed by Austrians during renovation of the fortress in 19^th century. Thus, assuming that a) the line had existed at the time and b) Mongols had managed to breach it, looting of the houses could have happened within this line, as opposed to the third line (the citadel). Third possibility is that the Mongols had managed to breach the fortress which had no further walls behind, but were repulsed after looting some houses within. However, the problems Mongols tended to have with European stone fortifications make these interpretations somewhat unlikely, as does the general Mongol discipline that made them less prone to looting before the battle had been won. Also making them unlikely is the fact that there might have been a settlement atop the cliffs, just outside the fortress, as the fortress itself was originally a location of an (Illyrian) settlement. Lastly, the text is actually very short, which makes it unlikely that houses will have been mentioned if they were, in fact, a part of the fortress – in such a case, it would have been sufficient to state merely that fortress was looted.

The Mongols did take away “no little plunder”, but this was likely sheep, rather than material valuables.

Thomas of Split claims that Mongols had abandoned the siege because they had learned Bela IV was not there. But there is no indication as to where he could have learned that – at best, it is his own speculation, based on the fact that Mongols were, in fact, pursuing Bela. The events could easily be reconstructed as Mongols failing in their attack on the fortress, settling in for a protracted siege or simply retreating to a camp outside, and then abandoning the siege or leaving either due to logistical concerns or because of the news that Bela IV was elsewhere. This is a far more likely course of events. It does not require Mongols to have taken the fortress and searched it room by room to ensure Bela IV was not hiding inside, which is contrary to sources which are clear that Mongols did not take the fortress. It also does not require a nearly supernatural timing which would have been required for a message to stop the Mongols just as they were about to capture the fortress.

Mongols had followed Bela IV to Split and then to Trogir. While both cities are obvious choices for a refuge, fact that they did it in the same order as the king does show some slight indications that they were indeed following Bela’s movements. This is also supported by the timeline:

1. In March 1242., Mongols were under Split. They did not besiege it, but merely slaughtered whoever was left outside the walls before going towards Klis.
2. Mongols, having heard that Bela is in Klis, besieged and attacked the town, but were repulsed.
3. Batu-khan learned that Bela was in Trogir, and went there, but had to retreat.
4. Mongols were then defeated near Šibenik.

One should also be wary of overstating the Mongol strength. Contemporaries were liable to do so – overstating both the power of Mongol armies and the damage they had wrought – due to the newness of the experience and Mongol victories in field battles. Because of this psychological impact that the Mongols had wrought, Thomas’ assertion that Mongols left Klis merely because they had learned Bela was not there, as opposed to being unable to take the fortress, must be taken with reserve.

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