The best lesson is taught by history. Conatantinople fell in 1453 and is now Istanbul. As Santayana said, "Those who do not remember the past are condemned to relive it".
In this global struggle against Islamofascism too many havn't remembered the past.
And, of course, that past, indeed the entire history of the Roman Empire from the retirement of the last Western Augustus to a villa near Naples in 476 until its actual fall in 1453, is not merely forgotten the way school history is, but is not taught at all, or if taught falsified with the name 'Byzantine', and lies about the Muslims 'preserving' classical learning they cribbed from the Christians who had preserved it.
Its full of facts, starting with the fall of Constantinople in 1453, when Mehmet II celebrated with beheading and sodomizing, and some lucky lads found themselves on the receiving end of both. This section is a lively read in an age when most westerners, consciously or otherwise, adopt the blithe incuriosity of Jimmy Kennedys marvelous couplet in his 1950s pop hit Istanbul (Not Constantinople):
Why did Constantinople get the works?
Thats nobodys business but the Turks.
Now, the curious thing is that, although in Turkish popular usage, for centuries, the city was called Istanbul (a Turkish corruption of the Greek 'eis politas', meaning 'to the City'), even as in the popular usage of the Greek-speaking Romanoi befor them, it was simply "the City", the official name was not changed by the Ottoman sultans, who were proud of their conquest of the city of Constantine, but only officially changed to Istanbul by the secularist New Turks who overthrew the Sultan (and Caliph--hey, any Sunnis on the board, remind your coreligionists it wasn't the US or the Brits or the French who abolished the Caliphate, it was the Turks).