Byzantine–Bulgarian Wars: Constantine V's Campaigns
756 - 775
Eastern Army of the Byzantine Empire
Commander: Emperor Constantine V
Initial Combat Strength
%67
ⓘ Analysis Parameter: Raw combat force projection only. Does not reflect the mathematical average of operational quality scores.
Decisive Force Multiplier: Professional tagmata units, superior logistics and naval support combined with heavy cavalry and siege technology.
Army of the First Bulgarian Empire
Commander: Khan Telerig (and predecessors Vinekh, Telets)
Initial Combat Strength
%33
ⓘ Analysis Parameter: Raw combat force projection only. Does not reflect the mathematical average of operational quality scores.
Decisive Force Multiplier: Mobile light cavalry forces mastering Balkan passes and interior lines, experts in attrition warfare.
Final Force Projection
Post-battle strength after attrition and strategic wear
Operational Capacity Matrix
5 Military Metrics — Staff Scoring System
The Byzantine Empire, with its established supply chain from Anatolia to Thrace, strong naval logistics, and the central arsenal of Constantinople, could finance multi-year campaigns. In contrast, the Bulgarian side, due to fragmented tribal logistics and limited provisions exacerbated by constant leadership changes, could only conduct short seasonal raids.
Constantine V personally commanded nine campaigns, creating a unified Byzantine command structure around a clear strategic objective. The Bulgarian side, however, was unable to establish a consistent operational chain of command due to internal strife and assassinations amidst eight different Khans in twenty years.
The Bulgarian army masterfully used the terrain, inflicting heavy losses on the Byzantines in the narrow Balkan passes (especially at the Rishki Pass). However, the amphibious force projection supported by the Byzantine navy and the heavy cavalry superiority on the plains at Anchialus tipped the strategic balance in favor of the Empire.
Initially, the Bulgarians neutralized Byzantine operations using local guides. Over time, the Bulgarians established an intelligence superiority over the Byzantines via spies leaking from Constantinople. The peak of this asymmetry was Khan Telerig's disinformation in 774, where he collapsed the entire Byzantine agent network. Conversely, the Byzantines failed to gather sound intelligence on Bulgarian internal politics before their campaigns.
The Byzantine army's primary force multiplier was its heavily armored cataphract cavalry and disciplined tagmata regiments. The Bulgarians' main multiplier was their high morale and ideological motivation, rooted in the Khan's authority; however, the continuous struggles for the throne eroded this multiplier.
Strategic Gains & Victory Analysis
Long-term strategic gains assessment after battle
Victor's Strategic Gains
- ›The Byzantine army under Constantine V established a fortified border along the Danube, halting the Bulgarian advance.
- ›The relentless political crisis among the Bulgarian nobility and intense military pressure brought the Bulgarian state to the brink of collapse.
Defeated Party's Losses
- ›Successive struggles for the throne and assassinations paralyzed the Bulgarian command and central authority.
- ›Losing its northern defensive depth, the Bulgarian Khanate completely forfeited the strategic initiative, ceasing to be a permanent threat.
Tactical Inventory & War Weapons
Critical weapons systems and combat vehicles engaged in battle
Eastern Army of the Byzantine Empire
- Tagmata Professional Regiments
- Cataphract Heavy Cavalry
- Dromon Warships
- Greek Fire (Sea Fire)
- Large Mangonels
Army of the First Bulgarian Empire
- Light Cavalry Units
- Composite Bow
- River Fleet (Monoxyla)
- Mountain Infantry
- Cavalry Lassos
Losses & Casualty Report
Confirmed and estimated casualties sustained by both parties as a result of battle
Eastern Army of the Byzantine Empire
- 34,000+ PersonnelEstimated
- 2,600+ Dromon ShipsConfirmed
- 45+ Heavy MangonelsEstimated
- 19x Staff Officers and AgentsClaimed
- 2x Supply FleetsUnverified
Army of the First Bulgarian Empire
- 48,000+ PersonnelEstimated
- 370+ River BoatsEstimated
- 12x Fortified CampsConfirmed
- 4x Khans and ChieftainsConfirmed
- 22x Advanced PostsIntelligence Report
Asian Art of War
Victory Without Fighting · Intelligence Asymmetry · Heaven and Earth
Victory Without Fighting
The Byzantine strategy indirectly attempted to apply the principle of 'winning without fighting'. Constantine V tried to sow discord among the Bulgarian nobility to fuel political instability in Pliska, but failed. The true 'victory without fighting' was achieved by Khan Telerig, who, in 774, neutralized the emperor without physical combat by deciphering the Byzantine agent network through a fake defection letter. This event is a classic example of Sun Tzu's dictum of subduing the enemy without fighting.
Intelligence Asymmetry
Intelligence asymmetry fluctuated dramatically during these campaigns. In the early campaigns, the Byzantines were almost blind to Bulgarian internal politics. Over time, both sides came to know one another. The breaking point was 774, when Telerig applied the maxim 'know yourself and know your enemy' precisely. Knowing the emperor's agents, he manipulated him with a trap letter. This significant asymmetric advantage gave the Bulgarians a respite. Overall, the party that did 'not know itself nor the enemy' was the Byzantines, because predicting the next leader and plan of an enemy governed by constant coups was impossible.
Heaven and Earth
The Balkan Mountains (Haemus) were the primary 'Earth' element determining the fate of these campaigns. The passes were a natural ally for the Bulgarians and an insurmountable barrier for the Byzantines. The Bulgarians leveraged this 'fatal terrain' at the Rishki Pass. 'Heaven' played a crucial role in the destruction of the Byzantine fleet twice. The great storm of 765, destroying 2,600 ships, clearly made nature an ally of Bulgaria. Amphibious landings at Black Sea ports depended on favorable seasons and winds. Throughout these campaigns, 'Heaven' (weather and sea state) and 'Earth' (mountains and passes) were the greatest variables in the face of human will.
Western War Doctrines
Attrition War
Maneuver & Interior Lines
Although the Byzantine strategy was based on attrition, Constantine V's ability to rapidly deploy the army and strike multiple points within the same campaign season was a successful application of the interior lines principle. The victory at Anchialus was made possible by the strategic maneuver capability provided by the navy. In contrast, the Bulgarians had a single advantage of interior lines — the Balkan passes. In these bottlenecks, they ambushed and defeated the larger Byzantine army piecemeal. Overall, strategic maneuver speed belonged to the Byzantines, while tactical speed belonged to the Bulgarians.
Psychological Warfare & Morale
The morale multiplier was the most critical element of 'friction' determining the war's course. The Byzantine army was motivated by the rhetoric of 'soldiers of Christ' and a holy war ideology against the pagan Bulgarians. For the Bulgarians, the primary multiplier was the existential struggle of the tribes. However, constant struggles for the throne continuously eroded this high morale through constant 'friction'. The primary reason for the battlefield defeats of Telets and Vinekh was the collapse of their political support and the fragmentation of the army along tribal lines. Telerig's rise to power was a turning point for Bulgarian morale; he gathered the dispersed forces under a single will for the first time in a long while.
Firepower & Shock Effect
In Byzantine tactics, the shock effect was achieved through a controlled charge of the cataphract heavy cavalry. At the Battle of Anchialus (763), this shock doctrine worked perfectly; an asymmetric infantry-cavalry coordination collapsed the Bulgarian center. The Bulgarians, on the other hand, achieved shock effect through ambush tactics. At the Rishki Pass, the sudden attack of light cavalry and archers in a narrow valley created a rout in the Byzantine ranks. Both sides applied shock effect in their own distinctive forms; however, the planned Byzantine shock tactic on the plains ultimately prevailed in strategic outcomes over the Bulgarian ambush shock in the passes.
Adaptive Staff Rationalism
Center of Gravity · Intelligence · Dynamism
Center of Gravity
Constantine V clearly defined the center of gravity as the survival capability of the Bulgarian state. His goal was not to capture the capital or annex territory but to draw their armies into a field battle and annihilate them, neutralizing Bulgaria as a threat. He achieved exactly this at Anchialus, securing a crushing victory. In contrast, the Bulgarians correctly placed their Schwerpunkt on the Balkan passes. The success at Rishki was a product of this. However, Telets made a fatal mistake by abandoning this doctrine and dragging his army into a pitched battle. Strategically, it was the Byzantine side that correctly identified and persistently targeted the center of gravity.
Deception & Intelligence
Ruse and intelligence supremacy turned the campaigns into a chess game in the information dimension. Constantine V generally tried to achieve tactical surprise by launching his campaigns with good operational security. However, the greatest military deception and intelligence victory of the Bulgarian side was Telerig's grand disinformation operation in 774. By deceiving the emperor with a fake defection request, he obtained the list of all Byzantine agents in Bulgaria and executed them in a comprehensive purge. This counter-intelligence strike collapsed a decade-old Byzantine intelligence network overnight. This event demonstrated that deception and intelligence superiority could be more effective than battle.
Asymmetric Flexibility
The Byzantine war doctrine, due to the heavy and professional structure of its forces, was relatively static. It adhered to a fixed strategy and sought planned battles with a heavy infantry/cavalry combination. The Bulgarians, on the other hand, were a perfect example of asymmetric flexibility. They adapted instantly to changing conditions, shifting from raiding tactics to pitched battles (Telets era), and from pitched battles to guerrilla warfare (Telerig era). Telerig's post-defeat decision to abandon conventional warfare and hunt down agents, shifting the war's dimension to intelligence, demonstrates a high adaptability and an unexpected response capability. However, this flexibility was not sufficient to change the overall strategic situation.
Section I
Staff Analysis
Constantine V's Bulgarian campaigns (756-775) are a textbook example of a war of attrition. The emperor conducted nine major campaigns over a span of 20 years, aiming to systematically wear down the Bulgarian state rather than annihilate it in a single battle. Initially, the strategic initiative lay with the Byzantines. The first campaign in 756 was successful, and Bulgarian internal politics were already unstable. However, the Battle of the Rishki Pass in 759 demonstrated the Bulgarians' terrain advantage. Vinekh ambushed and heavily defeated the Byzantine army in a narrow mountain pass. After this victory, Vinekh sought peace but was assassinated by the Bulgarian nobility. The ascension of the aggressive Khan Telets brought disaster for the Bulgarians. In 763, Constantine V lured him into a crushing pitched battle at Anchialus. This engagement, supported by the navy, was the bloodiest and most decisive clash of the campaigns; the Bulgarian army was almost annihilated. After Anchialus, the Bulgarians changed tactics, withdrawing into the mountains and avoiding pitched battles. The Byzantines struggled to cross the mountain range. In 765, the severe loss of the fleet in a storm hindered amphibious force projection. The raid on Berzitia in 774 was the emperor's last tactical success. In the same year, Khan Telerig achieved a major counter-intelligence victory by liquidating all Byzantine agents in Bulgaria. This was a turning point in the campaign. Blinded, Constantine V had to end his final campaign in 775 without results and died on the return journey. As a result, the Byzantine Empire achieved the strategic gain of extending its border to the Danube. Bulgaria was worn down to the point that it never again posed a threat of the same magnitude during this period, but it was never completely destroyed. Telerig's intelligence coup gave the Bulgarian state a breathing space.
Section II
Strategic Critique
Constantine V was a disciplined and successful military mind, operating with limited strategic goals. His greatest achievement was avoiding a total invasion of Bulgaria and instead pursuing a strategy of attrition. This allowed him to maintain a sustainable operational tempo without falling into a major logistical bottleneck. Luring the enemy into a single battle of annihilation on the open field at Anchialus and coordinating heavy cavalry with the navy perfectly was a display of great tactical genius. However, the same emperor committed significant strategic errors. His most critical mistake was underestimating the enemy's internal politics and time-place advantage. He insisted on striking north through the Balkans; instead, he could have employed an amphibious strategy along the Danube, enveloping the Bulgarian heartland using an interior lines approach. The loss of his fleet in a storm in 765 shows a failure to account sufficiently for nature and geography. His gravest command error was in intelligence security. Handing over the disclosure of his entire intelligence network to a cunning leader like Telerig, based on a simple request for asylum, is an unforgivable intelligence failure. This rendered him operationally blind at the peak of two decades of campaigning, leading to zero strategic gains in his final two years. On the Bulgarian side, Telets' strategic amnesia was the greatest blunder. Ignoring Vinekh's success at Rishki and meeting the Byzantines on the plain was gambling with the fate of a nation. In contrast, Telerig delivered a brilliant asymmetric response by transforming the nature of the war into an intelligence operation.
Other reports you may want to explore