Parkinson’s most famous law goes: Work expands so as to fill the time available for its completion.

But Parkinson’s most perceptive law tells us: The success of any policy is measured by the catastrophes that do not occur.

On Day One of this necessary war, Saddam Hussein launched an Ababil-100 low-flying missile. This missile is banned by U.N. sanctions, and never found by the U.N. inspectors -- but that's another story, and one already oft told.

Anyway, Saddam's missile was aimed squarely at the Camp Doha command post for the Coalition land assault. Had it hit, American and British commanders of the land war may well have perished. This crucial Coalition headquarters could have been wiped out.

But it didn't hit. Rather, it was hit.

Sirens wailed. Commanders hurriedly grabbed their protective gear to protect against a chemical attack. And very quickly, two PAC-3 missiles were fired.

The first one -- ironically, the first new-generation Patriot ever fired in combat -- hit the Iraqi missile head-on a mere five miles from the headquarters. The second, back-up PAC-3 -- to provide redundancy and ensure no weapons of mass destruction will ever get through -- consequently blew itself up, since its brethren had already done the job.

A major catastrophe did not occur. With typical British understatement, the Chief of Staff of UK forces, Gen. Peter Wall, deadpanned during an early CENTCOM briefing, "Were it not for the Patriot, many more lives could have been lost."

Several other modern weapons have saved Coalition lives and critical facilities. Yet the tale of PAC-3 is most dramatic, for several reasons.

First, for many years the Patriot program was barely kept alive by dogged Pentagon resistance to Congressional naysayers and budget-cutters. Following a rocky start, it gained ideological foes after President Reagan championed the SDI missile defense for the Nation. A workable regional defense might -- Star War mockers feared -- lend credence to Reagan's dream.

Second, Patriot went from champ during the first Gulf War, to chump right afterwards. It was initially hailed in 1991 for shooting down some 40 of the 80 Iraqi SCUD missiles Saddam fired at U.S. troops and at Israel.

Yet subsequent studies showed scant success. Israeli defense experts told me in 1993 that the original Patriot failed to shoot down any Iraqi SCUD missiles. Regardless, it failed to destroy the SCUD that slammed into the barracks in Dhahran, Saudi Arabia, killing 28 American reservists and wounding another 98. This was the most fatal incident of the entire Gulf War.

Skeptics doubted the two upgrades -- PAC-2, which has proven effective during the past week of war, and PAC-3. A spokesman for the Pentagon's Missile Defense Agency, Rick Lehner, called PAC-3 "the most successful missile test program we've ever had."

But a test program is one thing. Effectiveness in war is quite another, and many initially worried.

Third, Patriot displays the type of "Revolution in Military Affairs" which Defense Secretary Don Rumsfeld has vigorously and valiantly championed.

Granted, its name "Patriot," launcher, and guidance system are the same as the old version. But PAC-3 is a different system, and not merely an upgrade to an existing system.

For George W. Bush, it's sure not his father's Patriot. To wit:

• PAC-3 launchers pack gobs more power, as each launcher holds a mere four PAC-1s or -2s, but sixteen PAC-3s;
• PAC-3s defend an area seven times as large at the old version;
• It destroys incoming ballistic missiles, whether high-flying SCUDs or low-flying Ababil-100s, and can also demolish enemy aircraft and cruise missiles; and
• Most critical, it really demolishes enemy weapons.

For PAC-3s don';t merely explode near an enemy system, but smash into it. Traveling at five times the speed of sound, it practically vaporizes an incoming missile warhead, likewise traveling at Mach 5.

A bullet hitting a bullet in the air, it totally annihilates whatever the missile carries, be it conventional munitions -- or chemical, biological, or nuclear armaments.

What a job it did during the first hours of this war. A major catastrophe did not occur. A liberation will, within a few weeks, now occur.

Kenneth Adelman is a frequent guest commentator on Fox News, was assistant to U.S. Defense Secretary Donald Rumsfeld from 1975 to 1977 and, under President Ronald Reagan, U.N. ambassador and arms-control director. Mr. Adelman is now co-host of TechCentralStation.com.