Black Death!
In the year AD 1271 first reports of a horrible plague arrived in Constantinople. Merchants brought news from far Asian countries of a horrible epidemic that the world has never seen before! There were some that urged the Emperor to close the borders and try to prevent its spread through Byzantine lands. There were also people who knew that closing borders would mean shutting down the entire trade – impossible feat, especially for a trade empire like Byzantium. Basileus knew that it would be impossible to prevent the spread of disease through the empire, with so many merchants and armies marching through its lands. If only he knew that this plague was not like any other seen in the past…
Finally in the end of AD 1271 first reports of plague started coming in from eastern provinces and from Black Sea colonies. Within weeks Black Death has spread through the empire killing tens of thousands, not even Constantinople was able to protect itself from it.
In a little bit over one year most powerful empire in the world was thrown into total chaos. Trade and commerce have died along with a major part of the population army was hit hard as well. The biggest problem was money, with no trade and no one to pay the taxes coffers were empty. Production has stopped, farming reached lowest levels yet and trade fleets were grounded. If that wasn’t enough the lack of money meant that there was no money to pay the soldiers. With army already paralyzed with the plague, lack of wages could mean an all out rebellion!
To counter that Basileus Leon issued one very desperate order: There was going to be a war with Seljuks. Powerful armies were formed and soldiers were told they can plunder anything in the enemy lands. It was the only way to keep an army content, maybe not the most chivalrous decision made by the Emperor but for sure one of the most important for the survival of the Byzantium.
Three huge armies were formed out of the remaining regiments and they were sent against biggest Seljuk cities in the area Sis, Antioch and Caesarea.
Desperate Times
By the time armies reached their destination the country was already in huge debt. The only way of keeping order both among civilian population as well as in the army was sacking and pillaging of enemy lands. When armies arrived at their destinations it was certain that Seljuk Empire got hit pretty hard with the plague. There were no armies opposing them along the way and all smaller towns and villages were deserted or full of bodies of their formed residents…

General Gennadios with his army was the first one to reach his target; the town of Antioch. By the time they laid siege they found out that Seljuks were no more in control of the city, residents furious with lack of protection from the plague have rebelled against their former rulers. City was eaten by disease, engulfed in flames and its residents were busy fighting each other.

Byzantine artillery was set up to spread the panic even further, and to make sure there will be no organized resistance by the time army is ready to assault.

Even though artillery barrage lasted long enough to damage the fortifications enemy morale was high enough to form some kind of resistance.

Enemy archers managed to set the siege towers on fire which slowed down the process of taking control of the walls.

Byzantine soldiers had to use ladders instead of the towers, but even that obstacle could not stop them from winning the battle!

When artillery finally broke through the gate Byzantine troops poured inside.

Infantry charged enemy barricades and broke through enemy troops in a matter of minutes. Desperate Turks tried running away only to find out there were no more places to hide.

Each of the defenders was killed to ensure there will be no one in town to think about rebelling against their new masters!
Unfortunately after capturing the town it became obvious that the plague was not entirely gone. Byzantine garrison became infected and loses were terrible, way higher than the ones after the battle.

Black Death has spread all through the empire and by AD 1273 there was not a single city, town or village that was not affected by it.