After Andronikos II took to the throne in 1282, the army fell apart and the Byzantines suffered regular defeats at the hands of their eastern opponents, although they would continue to enjoy success against the Latin territories in Greece.

By c. 1350 the Empire's inefficient fiscal organization and incompetent central government made raising troops and the supplies to maintain them a near-impossible task, and the Empire came to rely upon troops provided by Serbs, Bulgarians, Venetians, Latins, Genoese and Turks to fight the civil wars that lasted for the greater part of the 14th century, with the latter foe being the most successful in establishing a foothold in Thrace.

In Anatolia, the local support for the Ottoman conquerors grew daily, whilst in Greece the ravaging by the Crusader states, by Serbia, by Bulgaria, and earlier on by the Angevin Empire ended the region's prominence as a source of Byzantine levies.

[1] However, under Andronicus II the more professional elements of the army was demobilized in favor of poorly trained and cheaper militia soldiers.

[5][6] Even though the Empire had shrunk considerably by the time of Andronicus III's reign, he succeeded in assembling an army of 4,000 men for his campaign against the Ottomans.

[8] With a supreme effort, Constantine XI succeeded in assembling a garrison of 7,000 men (included 2,000 foreigners) to defend the city against the Ottoman army.

Under Andronicus II however, the army was reduced to destructively low numbers – mercenary troops were disbanded to save money[15] and to lower taxes upon the disgruntled population.

The deployment of up to 20,000 Turkish soldiers from the Ottoman realm to assist her nominal Greek ally only eased future conquests of the area.

Since the Imperial treasury was bankrupt after c 1350, these foreign fighters fought only for political reasons and often in civil wars, rather than to strengthen Byzantium's position.

The key behind this approach was the use of border fortifications that would impede an invading force long enough for the main Imperial army to march in to its relief.

[2] One example of this occurred on May 1281 when Tarchaneiotes was sent by Michael VIII to relieve the fort town of Berat, and succeeded in driving Charles of the House of the Angevins away.

After the Imperial army suffered defeat in Asia Minor, Andronikos III saw Anatolia as a lost cause and began reorganizing the Byzantine fleet;[20] as a result the Aegean remained an effective defense against Turkish incursions until Gallipoli was at last captured by the Turks in 1354.

The crossbow was adopted by the Byzantine infantry in the 13th century,[23] although the Cypriote rebel Isaac Komnenos is recorded to have used crossbowmen as early as 1191.

Despite their relative rarity,[27] John Kantakouzenos approvingly referred to their efficiency in siege battles, while a new military office was also created, the stratopedarches ton tzangratoron.

[28] Gunpowder weapons were spreading in the Balkans from the second half of the 14th century and were well established by the 15th, but the Byzantines failed to adopt them on a larger scale because of the lack of money.

Even so, this was a longer period of time than the Crusaders in the Levant were able to hold out where impressive forts such as Krak des Chevaliers surrendered relatively quickly.

[34] Constantinople's fortifications remained formidable, but repairing them proved impossible after 1370 due to the destructive nature of an ongoing civil war.

By the time the Byzantines emerged from it, they were forced to acknowledge the suzerainty of the Ottoman Sultan, who threatened military action if any repairs were made to the millennium-old Walls of Constantinople.

The consequences did not simply mean an end to a Byzantine naval defense; it also meant an increased reliance on the unreliable Genoans and Venetians (who would consistently burn each other's property in the capital, thereby damaging the city) and left thousands of skilled sailors up for grabs by the Turks, who hired them to build their own fleets.

Still, the navy remained but one of many in the Aegean, which was also patrolled by Venetians, Crusaders, Turks and the Genoans, who evened the loss of Chios against the Greeks with the capture of Lesbos.

From the death of Andronicus III the Empire's civil wars gave the Venetians and Genoans plenty of naval warfare to dominate whilst the lack of a central government and resources worsened the navy further.