Pliska [Vǎrbitsa Pass] 811

Bulgars Versus Byzantines

The Turkic Bulgars appeared in the sixth century, first as a rump of the so-called Old Bulgarian Empire, the Kutrigurs, defeated by Belisarius outside Constantinople in 559, settled north of the Danube and were absorbed by the Avars. Following the collapse of Avar power in the eighth century, new Bulgar arrivals and existing elites in Transdanubia gradually formed the Bulgar khanate, which adopted Slavic language and customs. Given their cultural origins in the Eurasian steppe, it is unsurprising that throughout the medieval period the Bulgarian social elite fought mostly as heavy armed cavalry lancers. Bulgaria formed the most important state to the north of the empire. Though there were long stretches of peace between the two peoples and even alliance, Byzantine-Bulgar relations were strained by their fundamental conflicting goals—both empires sought to dominate the Balkans and each considered the presence of the other unacceptable. Thus the Bulgars sought to capture Constantinople or subjugate the Byzantines militarily, while the latter sought to contain or even annex Bulgaria outright.


Initially the Bulgars organized themselves along the lines of most steppe empires, with “inner” and “outer” tribes whose power relationships were articulated through marriage alliances, genealogies, and material exchange. Beneath the outer tribes in the pecking order were subject groups like Slavs, Greeks, and the mélange of Avar, Hunnic, and Germanic remnants that rendered the rich cultural matrix of the Danube basin. The khan stood at the pinnacle of an increasingly sophisticated hierarchy that developed under steppe and Byzantine influence. Senior “inner” nobles, called boilas (often Anglicized as “boyar”), and junior “outer” nobles, bagains, formed the elite of the Bulgar state and provided both the military leadership and elite troops of the khanate. The Bulgars matched their Byzantine foe with a strong hierarchical military organization with the khan in overall command while his leading generals, the tarqan, commanded his administrative regional center and presumably took the center of the battle line as well. The targan’s subordinates included komites (sing. komes), after Byzantine usage, who commanded the wings of the army. The highest-ranking Bulgar nobles were heavily equipped cavalry with barded mounts and relied on heavy household cavalry and lighter armed horse archers as did their steppe nomad ancestors.

Methods of Warfare

The Bulgars employed mass conscription to fill out the ranks for their armies. Fear was the main tool used to compel men to enlist and show up equipped for the occasion. Khan Boris Michael (d. 907) ordered that men who arrived for muster without proper equipment or unprepared for campaign were to be executed, as were those who deserted before or during battle. The rank and file included many Slavs who fought as light infantry, carrying shields and javelins. Bulgar cavalry resembled both their Byzantine enemy and other steppe nomads. The Bulgars were expert in their use of terrain, relying on ambush and surprise in their confrontation with the enemy. They demonstrated a high level of strategic planning, strong discipline, and military cohesion, and on numerous occasions were able to confront and defeat imperial field armies, as they did at Vǎrbitsa Pass in 811 when they trapped a large force led by the emperor Nikephoros I and destroyed it by hemming the Byzantines against a wooden palisade and surrounding it. The emperor himself was killed and his heir mortally wounded. The Bulgars were intimately acquainted with Byzantine military strategy and tactics and, unlike the fragmented Arab emirates to the east, formed a more unified foe unbowed by the shock of repeated defeats.

Byzantine Adaptation

The Byzantines dealt with the Bulgars via a full range of economic, diplomatic, and military strategies. Trade was limited by treaty to designated zones and monitored by imperial officials. Spies were maintained at the Bulgar court at Pliska; the Bulgar khan Telerig (768–77) tricked the emperor into revealing the identity of Byzantine agents among the Bulgars by the ruse of his promised defection, then slaughtered those in the pay of the empire. Byzantine failures against the Bulgars were often due to weakness in strategic and battlefield intelligence that resulted in the surprise of imperial field forces. Experienced and cautious commanders found warfare in Bulgaria perilous. Thus, in the ongoing dispute over control of lands in Thrace and Mesembria on the Black Sea coast, the emperor Nikephoros II Phokas mounted a brief campaign in which he found the Bulgars’ skillful use of the mountainous terrain and difficulties of supply and communication hard to overcome. Nikephoros therefore induced Sviatoslav I of Kiev to invade Bulgaria; the Rus’ captured scores of Bulgarian towns and fortresses and overwhelmed Bulgar resistance, which led to a direct confrontation between the Rus’ and their new Bulgar subjects and Byzantium. John I Tzimiskes’s defeat of the Rus’ at Dorostolon in 971 opened the way for Byzantine annexation of Bulgaria.

The Bulgars and the Byzantines had a joint history of battles in barricaded passes. In 811 the Byzantine Emperor Nicephoras I laid waste to Bulgaria and burnt the capital Pliska of Krum Khan of Bulgaria. On hearing that the Bulgarians were defending the passes, Nicephoras set out for the Vǎrbitsa Pass on the route back to Constantinople where the Bulgars had built a wooden wall. The Byzantines tried to burn the barricade and were either themselves burned or drowned in the moat built behind the wall.

Vǎrbitsa Pass

Nikephoros had evidently mobilized imperial forces on the largest possible scale to defeat Krum as the Romans might have done, with overwhelming force. To add more mass to the trained, drilled, and organized thematic forces, he had also recruited untrained irregulars fighting for cash (“many poor men”). Mass worked.

“The Byzantine Chronicle of the Year 811.” The Chronicle:

When . . . the Bulghars learned of the size of the army he brought with him, and since apparently they were unable to resist, they abandoned everything they had with them and fled into the mountains.

In an exemplary tale of the downfall of the wicked, there must be spurned opportunities for salvation:

Frightened by this multitude . . . Kroummos asked for peace. The emperor, however, . . . refused. After making many detours through impassable country [a misunderstanding or misrepresentation of maneuver warfare] the rash coward recklessly entered Bulgaria on 20 July. For three days after the first encounters the emperor appeared to be successful, but did not ascribe his victory to God.

The Chronicle adds numbers, even if too large given the earlier assertion that the Bulghars had fled into the mountains:

[Nikephoros found] there an army of hand-picked and armed Bulghars who had been left behind to guard the place, up to 12,000, he engaged battle with them and killed them all. Next in similar fashion he faced another 50,000 in battle, and having clashed with them, destroyed them all.

Subsequent events do indicate that the casualties of Krum’s palace guards and elite forces were indeed heavy.

Next came the looting of Krum’s palace, made of wood but more than the rustic hall of a barbarian chief-the Chronicle says of Nikephoros that while “strolling up the paths of the palace . . . and walking on the terraces of the houses, he exalted and exclaimed `Behold, God has given me all this.'” Moreover, the palace was filled with the accumulated riches of past depredations. Unwilling to give Nikephoros any credit for having conquered Krum’s capital and treasury, Theophanes instead stresses his avarice: “He placed locks and seals on the treasury of Kroummos and secured it as if it was his own.” The Chronicle to the contrary presents a generous Nikephoros:

[He] found great spoils which he commanded be distributed among his army as per the troop roster. . . . When he opened the storehouses of [Krum’s] wine he distributed it so that everyone could drink his fill.

What ensued was pillage and destruction. The Chronicle:

[Nikephoros] left impious Krum’s palace, and on his departure burnt all the buildings and the surrounding wall, which were built of wood. Next, not concerned with a swift departure, he marched through the midst of Bulgaria. . . .

The army . . . plundered unsparingly, burning fields that were not harvested. They hamstrung cows and ripped the tendons from their loins as the animals wailed loudly and struggled convulsively. They slaughtered sheep and pigs, and committed impermissible acts [rape].

Theophanes inserts another missed opportunity to avert disaster:

[Krum] . . . was greatly humbled and declared: “Behold you have won. Take, therefore, anything you desire and depart in peace.” But the enemy of peace would not approve of peace; whereupon, the other [Krum] became vexed and gave instructions to secure the entrances and exits of his country with wooden barriers.

Evidently Krum was able to rally the Bulghar warriors who had fled into the mountains, and others too from farther afield. In the Chronicle, Nikephoros proceeds from hubris to lethargy, conceding the initiative to Krum:

After he had spent fifteen days entirely neglecting his affairs, and his wits and judgment had departed him, he was no longer himself, but was completely confused. Seized by the torpor of false pretension, he no longer left his tent nor gave anyone an instruction or order. . . . Therefore, the Bulghars seized their opportunity. . . . They hired the Avars [a remnant by then] and neighboring Slav tribes [Sklavinias].

Krum’s forces converging on the leaderless Byzantines, who had scattered to loot, employed a characteristic and unique Bulghar technique: the rapid assembly and emplacement of wooden palisades of logs bound with twine across the full width of narrow valleys, erecting “a fearsome and impenetrable fence out of tree trunks, in the manner of a wall” according to the Chronicle. These palisades were not fortifications that could resist a siege, but they could protect troops launching missiles from behind them, essentially negating the archery of the Byzantines while allowing the Bulghars to use their own bows through slits in the palisades-as former steppe nomads, many Bulghars must have retained both composite reflex bows and the skill to use them. Fighting barriers like expedient obstacles are efficient insofar as they are not easily circumvented. But according to the Chronicle, the Bulghars did not wait for the Byzantines to run into their palisade ambushes on their way home; instead they attacked, achieving complete surprise that induced a panic flight that in turn ended in massacre:

They fell on [Byzantine soldiers] still half asleep, who arose and, arming themselves, in haste, joined battle. But since [the forces] were encamped a great distance from one another, they did not know immediately what was happening. For they [the Bulghars] fell only upon the imperial encampment, which began to be cut to pieces. When few resisted, and none strongly, but many were slaughtered, the rest who saw it gave themselves to flight. At this same place there was also a river that was very swampy and difficult to cross. When they did not immediately find a ford to cross the river, . . . they threw themselves into the river. Entering with their horses and not being able to get out, they sank into the swamp, and were trampled by those coming from behind. And some men fell on the others, so that the river was so full of men and horses that the enemies crossed on top of them unharmed and pursued the rest.

According to the Chronicle, there was but one palisade, which only intercepted fleeing remnants and was unmanned, rather than a fighting barrier:

Those who thought they had escaped from the carnage of the river came up against the fence that the Bulghars had constructed, which was strong and exceedingly difficult to cross. . . . They abandoned their horses and, having climbed up with their own hands and feet, hurled themselves headlong on the other side. But there was a deep excavated trench on the other side, so that those who hurled themselves from the top broke their limbs. Some of them died immediately, while the others progressed a short distance, but did not have the strength to walk. . . . In other places, men set fire to the fence, and when the bonds [which held the logs together] burned through and the fence collapsed above the trench, those fleeing were unexpectedly thrown down and fell into the pit of the trench of fire, both themselves and their horses. . . . On that same day the Emperor Nikephoros was killed during the first assault, and nobody is able to relate the manner of his death. Injured also was his son Staurakios, who suffered a mortal wound to the spinal vertebrae from which he died after having ruled the Romans for two months.

Nikephoros was the first Roman emperor to die in battle since the Goths killed Valens on August 9, 378, at Adrianople, but the catastrophe of July 811 was even more dangerous because there was no spare emperor ready to exercise control, as the western emperor Gratian did in 378 until he appointed Theodosius as Augustus of the east in January 379. Moreover, the victorious Bulghars were within two hundred miles of Constantinople, unlike the Goths, who were a very long way from Rome when they won their victory.

As Krum offered barbarian toasts from the skull of Nikephoros, lined with silver in the usual manner, all seemed lost. Nikephoros had gathered every mobile force to overwhelm the Bulghars, so there was nothing left to stop them from seizing Constantinople after his ruinous defeat.

But there is a lot of ruination in an empire. In the east, the Abbasid caliphate, the greatest threat of all under the formidable HarÄn al-RashAd till his death in 809, was paralyzed by the war of his son Abu Jafar alMaUmun (“Belief”) ibn Harun against his other son, the reigning caliph Muhammad al-Amin (“Faith”) ibn Harun, whom he beheaded in 813. Hence field forces from the Armeniakon and Anatolikon themes could be summoned to help defend against the Bulghars. To lead them, there was at first only the badly wounded and unpopular Staurakios, son of Nikephoros, hastily proclaimed emperor in Adrianople on July 26; but on October 2, 811, he was forced to abdicate in favor of his brother-inlaw Michael I Rangabe, chief palace official (kouropalates), who gained the favor of Theophanes by repudiating Nikephoros to embrace Orthodox piety, by gifts of fifty pounds of gold to the patriarch and twentyfive pounds to the clergy, and by ordering the execution of heretics.

Michael readily went to fight, but unsuccessfully, and on July 11, 813, he abdicated in favor of the wily and battle-experienced Leon V (813- 820), former strategos of the Anatolikon theme, who allowed Michael and his family to live peacefully as monks and nuns, after castrating his sons. So by the time Krum tried to attack Constantinople in earnest, there was a fighting emperor ready to defend the city.

One reason why Krum delayed so long was that he had lost many or most of the troops who had guarded his palace-probably his only veritable soldiers, as opposed to Bulghar warriors who might be summoned to war and fight very well, but who were not “hand-picked and armed” and readily commanded. A second reason is that Krum could not attack Constantinople effectively without a fleet to blockade the city and starve it out eventually, or siege engines and the siegecraft to use them to breach the Theodosian Wall. The Bulghars were former mounted warriors of the plains who had also learned to fight very well on foot and in the mountains, but ships, shipping, and naval warfare remained outside their ken. Byzantine defectors were duly found and hired to provide the necessary siegecraft-Theophanes mentions a converted Arab expert, antagonized by the avarice of Nikephoros, of course-but it all took much time, and the necessary machinery was not constructed and ready until April 814, too late for Krum, who died on April 13, leaving an ineffectual successor. By then he had won another major battle at Versinikia on June 22, 813, overrun much Byzantine territory in what is now again Bulgaria, and Thrace, conquering its largest city of Adrianople and many smaller places; but the empire survived, and would one day recover all its lost territories.

The defeat of 811 was not caused by a lack of training or equipment, nor by tactical incompetence or even operational-level shortcomings. It was a fundamental error at the higher level of theater strategy that placed the Byzantine forces at a very great disadvantage, which only prompt and fully successful operation-level actions could have compensated and overcome. Carl von Clausewitz explains in his On War why no defense against a serious enemy should ever be conducted in mountains, if it is at all possible to defend in front of them instead or even behind them, if necessary conceding the intervening territory to temporary enemy occupation.

It is true that mountain terrain offers many opportunities to establish easily defended strongholds, and narrow valleys offer many opportunities for ambushes. Both strongholds and ambushes can magnify the tactical strength of defending forces, allowing the few to prevail against the many at any one place. But if the army is thus fragmented by mountain terrain into many separate holding units and ambush teams, even if each one of them is tactically very strong, the overall defense is bound to be very weak against enemy forces that remain concentrated in one or two vectors of advance. The few defenders holding each place would then confront massed enemy attackers who can break through ambushes and overrun strongholds to advance right through the mountains, leaving most defending forces on either side marooned in their separate strongholds and ambush positions that were not attacked at all.

When the field army of Nikephoros advanced irresistibly all the way to Krum’s capital at Pliska, it left Bulghar forces impotently scattered in mountains and valleys. In their tactically strong but strategically useless positions, they could not resist the Byzantine advance nor defend Krum’s rustic palace. But they also remained unmolested by the Byzantine advance, and could therefore rally into action once they were summoned for Krum’s counteroffensive against the Byzantines, now cut off a long way from home by the Bulghars in between. None of this could have happened if Nikephoros had read his Clausewitz, therefore concentrating all his efforts against Krum’s army instead of Krum’s palace. With Bulghar strength destroyed, Nikephoros could have had the palace and everything else without fear of a counteroffensive. Having mobilized the tagmata, thematic field forces, and irregulars and led them into Thrace, Nikephoros should have slowed down his advance or even stopped altogether for long enough to allow Krum to assemble his own forces. The resulting frontal battle of attrition would have been hard, no doubt, with heavy casualties, but given their numerical superiority if nothing else, the Byzantines would have won. Then Nikephoros could have settled down to reorganize the newly regained lands into taxpaying territories, confident that no significant Bulghar forces remained behind to attack him.

Alternatively, if Krum refused combat, Nikephoros could have advanced on Pliska to seize the palace just as he did, but then he should have swiftly retreated back into imperial territory, before the Bulghars could gather to interpose themselves between the Byzantine army and its home bases. That retreat, moreover, would have had to be conducted as carefully as if it were an advance, with scouts ahead and flanking forces to counter ambushes, and battle groups ready to break through Bulghar palisades.

The only way of remaining in Pliska and the conquered lands even though most Bulghar forces remained undefeated would have been to keep the Byzantine army concentrated and ready for combat at all times, to fight off any and all Bulghar attacks. But it is hard for occupation troops tempted by easy looting to retain their combat readiness, and such a choice would have been very dangerous strategically in any case, given that the empire had other enemies besides the Bulghars, starting with the Muslim Arabs whenever they were not divided by civil war.

Because in the event Nikephoros did not redeem his fundamental error of theater strategy, the untrained “poor men” with their clubs and slings were just as good or just as bad as the finest tagma in the field: both were equally cut off strategically and outmaneuvered operationally by Krum’s Bulghars.


Victory went the other way in 1014 when Bulgar Khan Samuil built a wooden wall across the pass at the village of Klyuch, or Kleidion meaning key, in the Haemus Mountains which provided the main invasion route into Bulgaria. In the summer of 1014 the army of Basil II was repelled at the wall. Again, a path behind the wall was found and the Bulgarians were overwhelmed.

The subjugation of Bulgaria took decades, however, with persistent and arduous campaigning by the emperor Basil II, who reduced each quarter of the Bulgar state through sieges and attrition, finally grinding down Bulgar resistance. Bulgaria provided another test for Byzantine strategies of attritive warfare: imperial forces used sieges, scorched earth, and incremental capture-and-hold methods to gradually expand their bases of operations and finally wear out a formidable, skillful, and disciplined opponent. Although the empire possessed a dominant position in Bulgaria by the death of Basil II in 1025, serious resistance continued to the death of the Bulgarian tsar Peter II in 1041. Byzantine control of Bulgaria, won over decades of bitter warfare, lasted for nearly a century and a half.