War had come to the Land of Pleasant Living: A Coast Guard cutter at the Baltimore docks was blown up with plastic explosives, as was the oil terminal at Piney Point in St. Mary's County.

But the Thomas Point Lighthouse south of Annapolis was saved after alert guardsmen foiled a daring enemy attempt to approach the point in mufti.

On one side were the "enemy" -- Navy and Army commandos. On the other were the defenders -- 387 Coast Guard and Coast Guard Auxiliary officers. They had converged on the bay early in April to test techniques for protecting the nation's largest estuary from enemy attack.

For two weeks, the warriors could be seen steaming in and out of Annapolis in an assortment of vessels, while cutters patrolled deeper waters at the mouth of the Severn River, in Baltimore Harbor and at the mouth of the Potomac.

"We didn't win all our engagements," said Coast Guard Capt. Ronald G. Pickup, commander of the Marine Safety Office in Baltimore, who commanded the defending forces. "We didn't expect to.

"But from those that we weren't successful in, I think lessons were learned. We gained valuable experience . . . and I think everybody is more ready than we were prior to the exercise."

The first week was devoted to planning and training for the defense of three targets: The Coast Guard cutter Red Birch, docked at Pier 6 at the Dundalk Marine Terminal in Baltimore; the Steuart Petroleum Co.'s docks, storage tanks and barges at Piney Point, near the mouth of the Potomac in St. Mary's County; and a "Mobile Inshore Undersea Warfare Unit" at Thomas Point.

The unit was, in fact, a van laden with electronic equipment parked near the edge of the water.

Inside it, electronics experts watched radar screens to detect incursions by land, sea and air, and monitored sound waves picked up by sonar bouys placed offshore to detect underwater movement by scuba divers.

During one week of round-the-clock efforts to seize the targets, the enemy attempted to approach the targets by land and by sea. Some came on pleasure boats and some in scuba gear. When Coast Guard officers challenged them and accused them of being the enemy, they were considered captured.

In one instance, Pickup said, two enemy boats approached the Dundalk Marine Terminal as a diversionary measure. While guardsmen from the picket boats boarded the enemy vessel to capture their crews, the enemy raced in at 35 knots in a small inflatable speedboat and plastered stickers on the Red Birch declaring that it had been blown up with plastic explosives.

But Pickup said many successful "penetrations" wouldn't have been made if there really was a war. Guardsmen would be posted on docks and beaches and would fire at attackers and their boats, he said.

In this exercise, no one was injured. "Everybody got in the spirit of it and really enjoyed it," Pickup said. But more importantly, they learned that in a real attack they would need more boats, more guardsmen, better weapons and more training, he said.

But even with those problems, Pickup said, the Navy Seals and Special Forces couldn't fool guardsmen posted at Thomas Point.

The enemy borrowed an Anne Arundel County ambulance, dressed up in ambulance drivers' uniforms, and rushed to the point at 2 a.m. with sirens wailing and lights flashing. "They said they were going to a medical emergency," Pickup said. But when challenged, he said, they were forced to admit they were the enemy and were taken prisoner.