When Constantinople finally fell to the Ottomans on Tuesday, May 29, 1453, the Byzantine Empire and its capital had up to that point survived for 1,000 years beyond the fall of the Western Empire at Rome.
Always outnumbered in a sea of enemies, the Byzantines' survival had depended on its realist diplomacy of dividing its enemies, avoiding military quagmires, and ensuring constant deterrence.
Generations of self-sacrifice ensured ample investment for infrastructure. Each generation inherited and improved on singular aqueducts and cisterns, sewer systems, and the most complex and formidable city fortifications in the world.
Brilliant scientific advancement and engineering gave the empire advantages like swift galleys and flamethrowers - an ancient precursor to napalm.
The law reigned supreme for nearly a millennium after the emperor Justinian codified a prior 1,000 years of Roman jurisprudence.
Yet this millennium-old crown jewel of the ancient world that once was home to 800,000 citizens had only 50,000 inhabitants left when it fell.
There were only 7,000 defenders on the walls to hold back a huge Turkish army of over 150,000 attackers.
The Islamic winners took over the once magical city of Constantine and renamed it Istanbul. It had been the home of the renowned Santa Sophia, the largest Christian church in the world for over 900 years. Almost immediately, this "Church of the Holy Wisdom" was converted into the then largest mosque in the Islamic world, with minarets to follow.
So what happened to the once indomitable city fortress and its empire?
Christendom had cannibalized itself. Western Catholicism and Eastern Orthodoxy fought endlessly. Westerners often hated each other more than they did their common enemy.
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.
Nowhere is it foreordained that America has a birthright to remain the world's preeminent civilization.
An ascendant China seems eerily similar to the Ottomans. Beijing believes that the United States is decadent, undeserving of its affluence, living beyond its means on the fumes of the past - and very soon vulnerable enough to challenge openly.
Left and Right seem to hate each other more than they do their common enemies.
Like the Byzantines, Americans gave up defending their own borders, and simply shrugged as millions overran them as they pleased.
Our once iconic downtowns, like end-stage Constantinople before the fall, are now dirty, half-deserted, dangerous, and dysfunctional.
America prints rather than makes money, as its banks totter near bankruptcy.
Americans similarly believe they are invincible without ensuring in reality that they are. Our military is more worried about being "woke" than deadly.
Like Byzantines, Americans have become snarky iconoclasts, more eager to tear down art and sculpture that they no longer have the talent to create.
Current woke dogma, obscure word fights, and sanctimonious cancel culture are as antithetical to the past generations of World War II as the last generation of Constantinople was to the former great eras of the emperors Constantine, Justinian, Heraclius, and Leo.
The Byzantines never woke up in time to understand what they had become.
So far neither have Americans.