Monte Porzio 1167 AD

[Erpingham]

Name of the Battle and Date  Battle of Monte Porzio (also known as Tusculanum), 29th May, 1167
Protagonists (opposing nations and generals) : Holy Roman Empire, led by Archbishops Christian I of Mainz and Reinald of Cologne v. City of Rome, commander unknown but probably Oddo Frangipani
Numbers if known  or a reasonable estimate Imperial approx. 1600, of whom 1200-1300 knights. 300 of the knights were in Tusculanum, the others in the relief army.  Romans 10,000-30,000 mostly militia infantry
The title of and chapter and verse of original source.
Chronicle of Otto of Saint Blasien, as published in Monumenta Germanica Historica Scriptores SS., 20.  English translator unknown, online at De Re Militari website
The Quotation about the battle in full

In the year 1166 since the birth of Christ, Emperor Frederick, after settling the conflict between the princes, as we have mentioned, and restoring good order to the situation in Germany, assembled an army from all parts of the empire and led it into Italy, crossing the Alps for the fourth time. Then he crossed the Apennines, and, leading his army through Tuscany, he turned to the March of Ancona, and surrounded the rebellious city of Ancona with a siege. In the meantime, Reinald, the archbishop of Cologne, who had previously separated himself from the emperor on imperial business, turned against the castle of Tusculanum near Rome, as he was returning with his corps to rejoin the emperor, in order to take care of the situation there. When this was reported in Rome by messengers, the Romans, whose strength was estimated as 30,000 armed men, moved out from the entire city and suddenly besieged the archbishop in the castle, to the dishonor of the emperor. As soon as this was reported to the emperor at Ancona, he assembled the princes and asked them whether or not he should give up the siege of Ancona and go to the aid of the archbishop. A few of the princes, most of them of the laity, who feared the spread of unfavorable rumors that would result from a lifting of the siege, advised against it. Angered by this agreement of the princes, because the lay princes had such small regard for him and his colleagues or abandoned them in danger, the stately archbishop of Mainz, Christian, called together his men and others whose aid he could enlist by pleas and rewards. He assembled 500 knights and 800 mercenaries (Caesarianos), appropriately equipped for war, and moved out toward Tusculanum against the Romans, in order to relieve the archbishop. When he arrived there and had pitched his camp opposite the Romans, he sent emissaries to them to request peace for that day only to allow his army to rest, recalling the virtue of the noble attitude that was characteristic of the ancient Romans. In this way, he hoped to win his demands from them. But the Romans themselves, completely unlike the ancients in this and all other respects, answered that they would not grant his request but arrogantly threatened that on this day they would give him and his entire army to the birds of heaven and the wild animals of the earth to eat. Giving up the siege, they formed 30,000 warriors in line of battle against 500 German knights. But the archbishop, completely unshaken by the answer he had received from them – for he was not inexperienced in the troubles of war – with great energy encouraged his men for battle by promises and threats. Even though their number was very small in comparison with their opponents, he knew they were battle-hardened fighters. He warned them in noble words that they could not place their hope in flight, since they were too distant from their fatherland and the emperor's army to be able to flee, but, mindful of their inherent courage and of the cowardice that was natural to their enemies, they should fight for their lives with all their strength.
But when he saw that the knights were filled with German fury (animositate Teutonica) – for his exhortation had injected a certain invincible courage in their hearts – he formed his lines and specified precisely which ones were to fight at first, which were to break into the fighting enemy forces from the flank, which ones were to bring help to those in trouble in the fight, while he himself took position where he could bring help with the most highly selected men. And now he moved into the fight against the Romans with raised banners and widely deployed cohorts, placing his hope in God. The archbishop of Cologne, however, armed himself and the garrison of the castle and all his men, a number estimated as 300 well-armed knights, in order to be able to give help under any circumstances, and he remained calmly in the castle until the start of the battle. After the battle had begun and the lances were broken at the first clash of the armies, the fight was carried on with swords, while the archers on both sides obscured the light of day with their arrows as if they were snowflakes. And behold, the archbishop of Cologne, breaking out of the castle with his eager knights, attacked the Romans from the rear and pushed against them courageously, so that they were surrounded on all sides, attacked from front and rear. While the Romans therefore were fighting only with the weight of their mass, Bishop Christian with his men penetrated their battle line from the flank, tore the middle of their formation apart, and covered with blows the enemy that was thus skillfully separated into three groups. After many had been killed and a number taken prisoner, the defeated Romans took to flight and, pursued by their conquerors up to the city, they were cut down in the bloodiest slaughter. After they had called back their knights from this butchery, the bishops returned to the battlefield and spent that night celebrating with the greatest joy.
In the morning the Romans hastened out to the battlefield to recover the corpses of their fallen. They were driven to flight by the bishops, who sent their knights out against them, and returning toward the city, they barely escaped death. Finally, they sent emissaries to the bishops to beg that they be allowed, for the love of Saint Peter and respect for Christianity, to recover their dead. The bishops granted this plea on the condition that they would count the number of men on their side that were killed or captured in this battle and would report this to them personally in writing with a sworn guarantee of their truthfulness, and that they could peacefully recover their dead for burial only after complying with this condition. When they went about this accounting, they found the number of some 15,000 of their men who had been killed or captured in this battle. After receiving permission, they buried the remains of their dead, which they recovered with loud lamenting.

Commentary
An interesting account of a battle almost unknown in the UK but described by the German historian Ferdinand Gregorovius in his monumental history of medieval Rome as "the medieval Cannae".  Gregorovius seems to have been influenced by the huge casualty rate and the fact that the Roman army is enveloped.
The casualty rate is actually a bit of an issue.  The quoted source states the Romans lost 15,000 killed and wounded from 30,000 combatants.  This is reinforced by a letter from Archbishop Reinald, one of the commanders, who claims 9,000 were killed and 5,000 captured.  But Italian sources all give smaller numbers present and smaller casualties, although some actually give a lower percentage of men who managed to flee to Rome, at only a third of the army.  One source gives casualties of 2,000 killed and 3,000 captured.  We might also note that it was believed the dead were buried at three churches on the Via Latium.  One of these had a memorial which stated 1166 casualties were buried there.  It is, therefore, quite plausible, of an army around 10,000, over half were killed or captured.  Imperial casualties are recorded in the post battle letter as zero.  It is a popular device in medieval battle reports to report miraculously low casualties on one's own side to emphasise divine favour, and one might expect this of an archbishop.  This wouldn't be believed if rumours were heavy casualties occurred so Imperial casualties were probably very low.
Turning to the tactics on display, the Imperialists appear to have quite a sophisticated plan.  We can see the attacking army is in at least three parts – a frontal attack force, a flanking force and a reserve.  In addition, they either co-ordinate with the garrison in Tusculanum, or these show good initiative to launch a rear attack when the Romans are engaged.  It is a good example of how a tight knightly force could carve up a much larger body of mediocre infantry.
There are a number of other takeaways here.  Not one but two killer archbishops, demonstrating the secular role of such clergy in the Holy Roman Empire.  Reinald would not long survive the battle – disease decimated the Imperial army a few months later – but Christian I would go on to be a major Imperial commander.  Gregorovius, summing up his career, calls him a "typical jovial knight" who was good with an axe.  Benjamin Arnold writes of him "In the battle for Bologna it was recorded that, clad in full armour and on horseback, the bloodthirsty prelate killed nine men with a triple-headed bludgeon" *. We also have an example of mass prisoner taking of commoners, though unfortunately no detail of how this happened.  An example too of the formalities of retrieving the dead.  This needed negotiation if the victors were still on the field.

* German Bishops and their Military Retinues in the Medieval Empire, German History Vol. 7 No.2, 1989

[Duncan Head]

Very interesting, Anthony, thank you. Nice to see an addition to this sub-forum, it's been a while.

[Andreas Johansson]

I agree with Duncan

How do you get 1200-1300 knights in the Imperial army, though? 500 with Christian and 300 in the castle should make 800, no?

The mention of archers on both sides presumably means that at least some of the mercenaries were such. Anyone know anything about the label caesariani for mercenaries? Pauly informs me the word originally meant members of the imperial household, and in Late Antiquity came to refer to a species of fiscal officials, but evidently it had undergone further semantic evolution by the 12C.

[Erpingham]

As you correctly note, it depends on what the caesariani are.  My guess would be either imperial household troops or imperial stipendary troops (hence mercenaries).  Other sources, according to Gregorovius, put the German army at under 1,000 cavalry, so this would favour a reading which made the caesariani foot.  Other sources also refer to the Imperial army containing Brabancons, which would suggest mercenaries, but not necessarily distinguish between foot and cavalry.  Some archers were clearly present on the Imperial side and, as such, presumably infantry but it would be a guess how many. 

[Andreas Johansson]

It seems to me that if Christian gathered "500 knights and 800 mercenaries/caesariani", the natural reading is that the latter were not knights.

Not that it necessarily makes a difference tactically speaking - "not knights" might include cavalrymen fighting just like knights but lacking the social status.

[Erpingham]

Not that it necessarily makes a difference tactically speaking - "not knights" might include cavalrymen fighting just like knights but lacking the social status.

Yes, apologies, that was slack of me.  I was thinking of them functionally the same but socially the situation would be more complex.  I'm not sure a German miles at this time would be the social equivalent of Brabancon one, or an Italian one (there were Apulian exiles in the Imperial army, presumably in small quantities).

[Mick Hession]

Thanks for this one Anthony: an interesting read.

Cheers
Mick