In the final days of Constantinople, almost no help was sent from Western Europe to the besieged city.

In fact 250 years earlier, the Western Franks of the Fourth Crusade had detoured from the Holy Land to storm the supposedly allied Christian City of Constantinople. Then they ransacked it and hijacked the Byzantine Empire for a half-century. Constantinople never quite recovered.

The 14 th-century Black Plague killed tens of thousands of Byzantines and scared thousands more into moving out of the cramped city.

But the aging and dying empire battled more than the challenges of internal divisions, or an unforeseen but deadly pandemic and the empire’s disastrous responses to it.

The last generations of Byzantines had inherited a global reputation and standard of living that they themselves no longer earned.

They neglected their former civic values and fought endless battles over obscure religious texts, doctrines, and vocabulary.

They did not expand their anemic army and navy. They did not reunite their scattered Greek-speaking empire. They did not properly maintain their once life-giving walls.

Instead of earning money through their accustomed nonstop trade, they inflated their currency and were forced to melt down the city’s inherited gold and silver fixtures.

The once canny and shrewd Byzantines grew smug and naive. Childlessness became common. Most now preferred to live outside of what had become a half-empty, often dirty, and poorly maintained city.

Meanwhile they underestimated the growing power of the Ottomans who systematically pruned away their empire. By the mid-15th century, Islamic armies were ready to exploit fatal Byzantine weaknesses.

The Sultan Mehmed II grandly announced the Ottomans were now the real, the only world power. Ascendant Ottoman armies would eventually move on to the very gates of Vienna in an effort to rule all the lands of the ancient Roman empire.

We should take heed from the last generations of the Byzantines.