Many participants in Saturday’s “peace” demonstration on the Mall — including mainstream media journalists covering it — noted the parallels with the anti-war movement of the Vietnam era. Thousands demanded American withdrawal from a nation under siege by totalitarians bent on enslaving millions. Hollywood celebrities and Democrat politicians stood shoulder-to-shoulder on the speaker’s platform. Sen. John Kerry, D-Mass., was even a weekend presence, via television from Switzerland, again telling the world how terrible is his country. All that was needed to complete this reconstruction in time was new photos of Jane Fonda consorting with insurgents killing Americans in Iraq in 2007, as she did with the North Vietnamese killing Americans in 1972.

There is, however, one fundamental difference between 1972 and 2007. We know today what comes after the marchers have boarded their buses and headed home, the speeches have ended and the politicians have voted their resolutions. Once the enemy celebrates their victory, blood begins flowing across the killing fields. In Vietnam, millions of South Vietnamese were murdered within weeks of the North’s April 1975 triumph, millions more spent years in brutal “re-education camps” and yet more millions became boat people fleeing the slaughter. In Cambodia, the Khmer Rouge created a Hell on earth that killed millions more innocents. Eventually, millions of Afghanis died because the Soviets were emboldened by America’s defeat in Vietnam to send the Red Army streaming into Afghanistan.

If the “peace” movement succeeds in defeating America again, the blood will again flow across the killing fields, but this time it will create even more unimaginable horror and it will not all be in distant lands far removed from our comfortable neighborhoods here at home. The slaughter of Shia and Sunni in the streets of Baghdad and elsewhere in Iraq will only be the beginning of the mass killing that will follow American defeat. With the Americans gone, al-Qaida will have a secure breeding ground from which to launch countless terrorists attacks against the U.S. and its allies around the world and here in America. Turkey will send troops into Northern Iraq and kill or otherwise eliminate all possibility of an independent Kurdistan. Jihadist radicals in Saudi Arabia, Pakistan, Egypt and elsewhere in the Muslim world will foment massacres, bombings and assassinations aimed at overthrowing remaining moderate regimes.

Worse yet, Iran will be emboldened to advance its timetable for becoming the dominant power in the Middle East and millions of Jews in Israel will be incinerated, along with hundreds of thousands of neighboring Palestinians, when the world sees the bright flash of Ahmadinejab’s nuclear program consumated in a second Holocaust.

It is difficult to say what America winning in Iraq will look like other than that a stable democratic regime will be in place and al-Qaida will be denied a new sanctuary. There is no such difficulty, however, in saying what America losing in Iraq will look like — a bloodbath of incalculable horror. Are the demonstrators and their allies in Congress and the media prepared to carry that burden on their consciences?