The Marine Corps is trying to get new mileage out of a 4-year-old recruitment ad, one of the most expensive ever produced by the Pentagon for television. The ad -- a medieval fantasy worthy of George Lucas or Steven Spielberg -- is now airing during Sunday afternoon football games.

The ad shows a knight in shining armor being dubbed by a king. With the help of lightning bolts, the knight turns into, what else, one of the few, the proud -- a Marine.

When the ad was produced in 1986, it cost taxpayers $355,000. That year the Marine Corps took in 35,000 recruits, up about 1,200 from the year before. Recruitment numbers dropped in 1987, rose slightly in 1988 and fell again last year to about 33,000. A Marine spokesman told our associate Scott Sleek that the service doesn't worry about big numbers. He said the ad was designed to attract people who have the qualities the Marines want.

For the kind of money the Marines spent on the ad, they should have stuck to reality. The Marines sweltering in the Persian Gulf waiting out Saddam Hussein would have a hard time identifying with King Arthur. And the news photos from the gulf will speak louder than the halftime hype of swords and sorcerers.

Television advertising is a big expense for the Pentagon -- $203 million this year for all the services. Until the knight in shining armor came along, ads produced for the Marines over the years averaged about $20,000. The most expensive for the Marines over the last five years had cost $77,000 to produce. The Army tops the Marine dollar figure spent on a single ad, but that ad at least has some relation to reality. It is the $555,046 ad showing a female soldier holding down a high-tech mobile communications post during a training exercise.

The Marines' "knight" ad is the best evidence yet that the Pentagon has a Hollywood fixation. The ad opens with blue lightning bolts coming out of a sword. Huge wooden doors open, and a knight rides his steed down the long hall of a medieval castle. An old monarch waits for him at the end of the hall, holding the sword spewing lightning. The knight kneels, the king taps him on the helmet and, voila, the knight is transformed into a modern Marine.

The Pentagon says television is its most effective recruitment tool. But instead of telling potential recruits that they will spend months sweating in the desert and staring at nothing but sand, the ads emphasize the nonmilitary perks of soldiering -- job training, education and world travel. The TV networks classify recruitment ads as a public service and often air them free.

The brass is eager to get free air time any way it can, including movie-length recruitment tools such as "Top Gun" and music videos filmed on battleships.

We reported last January that Cher finagled the use of a battleship and its crew for her video "If I Could Turn Back Time." There's no way of telling how many recruits were lured to the Navy by the vision of Cher gyrating in what passes for clothing and straddling a huge gun on the deck of the USS Missouri while 150 sailors cheered her on.