Some 13 centuries ago, radical Islamic fundamentalism burst upon the world, spreading in just a few decades across most of the Middle East and North Africa and threatening the very existence of the West.

In their expansion, the armies of Islam took advantage of the weakness of the worldÿs great powers at the time. Byzantium had just defeated Persia in a long war that had left both empires weakened. As Will Durant writes in The Story of Civilization, "¹both Byzantium and Persia, exhausted by war and mutual devastation, were in a tempting decline."

John Norwich echoes that view in A Short History of Byzantium, writing, "In one respect in particular, luck was on the side of the Arabs: the Byzantine-Persian war had left both Empires exhausted."

Within a few decades, the Muslim armies had utterly destroyed and completely conquered Persia, were at the gates of an apparently doomed Constantinople, and were pouring across the Pyrenees from Spain into France, bent on the subjugation and conversion of the West.

T hat they were stopped, that the West survived at all, is not far short of miraculous. Somehow Byzantium rallied. Constantinople survived two great sieges, the last ending in 718, and Byzantium subsequently went on the offensive against the Muslims. The Byzantine Empire ultimately survived another 700 years before falling to the Ottomans.

In 732, Frankish forces led by Charles Martel engaged Muslim forces near Poitiers in southern France and in what Durant called "one of the most crucial battles of history," won a great victory, perhaps saving Western civilization. Its limits roughly established, Islam flourished and then declined over the centuries.

Now, taking advantage of another power vacuum Ð the end of the Cold War, the collapse of the Soviet Union, and the strategic retrenchment and uncertainty of America in the post-Cold War world, radical Islamic fundamentalism has emerged onto the world stage again. This time it takes the form of stateless terrorism supported to varying degrees by totalitarian Islamic states in the Middle East, and by radical fundamentalist Muslims around the world.

But the goal of radical Islam is the same as it was 1300 years ago, the conquest of the West and the establishment of fundamentalist Islamic rule worldwide. They, the radical Islamic terrorists and those who support them, are at war with us and seek our defeat and conversion, whether we care to accept that fact or not.

Thirteen centuries ago the leaders of Byzantium and Western Europe understood the threat. They stopped radical Islam by the narrowest of margins by force of arms, guaranteeing through cold steel the ascendancy of the West, at least until our time.

So we in the West are left as we enter 2003 with two choices. We can pretend or we can fight. We can pretend we are not at war, we can pretend that our enemies want only peace, we can pretend that we can reason with people who fly loaded airplanes into buildings, and we can even pretend that this is all somehow our own fault. Or we can fight.

Once we recognize the need to fight, fighting means taking the battle to the enemy and his allies. That includes Iraq. Geographically and strategically, if not quite ideologically, Iraq, or more precisely Saddam Husseinÿs totalitarian regime in Iraq, is at the core of the entire rotten scaffolding of Middle Eastern terror and resurgent radical Islamic fundamentalism. Defeat Iraq and the whole rotten structure of hate just might come tumbling down. The destabilization of neighboring regimes such as Iran and Syria that might result from the defeat of Saddam, one of the bogeymen thrown up by those who oppose war, might just lead to positive change in those regimes, to their moderation rather than further radicalization.

And then we can deal with our other enemies before they deal with us, in a world suddenly more reminiscent of the 8th Century than the 21st. We can fight and win, as Byzantium and the Franks did. Or we can do nothing and await the next blow. And the next.