The Battle of Anchialus was a confrontation between the Byzantine Empire and the Bulgarian forces, occurring during the reign of Emperor Constantine V. Strategically significant, Anchialus was located near the Black Sea, making it a critical area for both empires vying for dominance in the region. The Byzantine army, well-organized and equipped, confronted the Bulgarians, who were seeking to expand their territory under the leadership of Khan Telec. The battle marked an apex in Byzantine military strategy, characterized by effective formations and innovative tactics that had been developed under Constantine V's initiative.

Emperor Constantine V, known for his military acumen, deployed his forces in a way that exploited the terrain and the elements, ensuring a comprehensive approach to warfare. The Byzantine army's experience and cohesion played a crucial role in their victory, ultimately leading to the defeat of the Bulgarian troops. This victory did not only repel the immediate Bulgarian threat but also fortified Byzantine positions in the Balkans, allowing for a more stable border and diminishing Bulgarian expansionist ambitions temporarily.

Following the battle, the aftermath saw a period of consolidation for the Byzantines, as they took advantage of the victory to reinforce their military presence in the region. This battle is often cited as a critical point in Byzantine-Bulgarian relations, setting the stage for future conflicts and negotiations.