The Grenada invasion was far from the well-oiled operation advertised at the time but was frequently saved from disaster by last-minute decisions of commanders in the field, including one that kept the Marines from blowing up the Venezuelan Embassy.

The picture of troops feeling their way into hostile territory without the benefit of maps, accurate intelligence, functional radios or protective artillery emerges strongly from a Marine after-action report obtained under a Freedom of Information Act request.

In separate interviews, officers involved in the Grenada operation underscored the lack of preparation and said casualties would have been much higher than the toll of 19 killed and 115 wounded had it not been for the ability of some officers on the ground and plain luck.

A big lesson of Grenada, according to the written reports and high-ranking officials interviewed, is that the world's least developed nations can obtain enough modern weapons to down helicopters. Therefore, sending helicopters into hostile areas without first suppressing defenses can be disastrous.

In the Grenada invasion, which started Oct. 25, 1983, the Marines lost three helicopters, two Cobra gunships and a CH46E, to enemy fire. The Army lost one Blackhawk troop-helicopter and had five others damaged, four seriously.

A high-ranking Navy officer on the scene said the guns on Navy ships standing off Grenada should have been used to suppress enemy fire before Army Blackhawk helicopters were sent in and before Army Rangers parachuted onto the the Point Salines airfield. The Army Rangers jumped from 500 feet, missing antiaircraft fire that Cubans had set for targets at 800 feet, officials said. The Rangers then ran into into heavy fire and armored vehicles on the ground.

Under the battle plan, code-named Operation Fury, the Marines were to secure the northern half of Grenada and the Army the southern half, with Air Force support. High-ranking critics said the Grenada operation would have been much smoother had only the Navy and Marines been involved rather than making it the kind of four-service enterprise that also complicated the unsuccessful 1980 attempt to rescue American hostages from Tehran.

"The wisdom is that everything has to be a four-service show," one top official said.

The Marine after-action report, obtained in the form of an unclassified report sent to Marine commands, documents how the 22nd Marine Amphibious Unit was caught by surprise as it was ordered to reverse course from Lebanon to Grenada. But it improvised on the ground to solve problems and avoid disaster.

The report states that charts of Grenada were "ungridded, small-scale or very outdated . . . . The original plan for the assault at Pearls airfield was to land one company by helicopter directly on the runway to achieve maximum shock effect . . . . Reasoning that an assault directly onto the runway could result in disaster if the airfield was heavily defended by enemy troops or protected by antiaircraft artillery sites, the decision was made to utilize another landing zone approximately 700 to 800 meters southeast of the Pearls airstrip. As it turned out, the airfield was protected by light AAA [antiaircraft-artillery.]"

The two Marine assault companies climbed into helicopters aboard the USS Guam and flew toward their landing zone in the pre-dawn dark of the 1983 D-Day, to land on what the charts and maps showed as a smooth race track.

"But when the helicopters dropped toward the landing zone, they encountered tall palm trees and unexpectedly high scrub brush," the report states. Pilots wearing special glasses that enhance night vision found a flat spot and landed the first Marines there.

Just as the Marines who secured the Pearls airfield were handicapped by inaccurate maps and charts, the ones flown toward Grenville to the south found that the landing zone chosen from the maps was unusable. The helicopter commander made a quick change and landed on a soccer field in the middle of the town without drawing fire.

"Throughout D-Day," states the report, the Marine battalion landing-team commander on shore "was restricted in the command and control of his remaining unlanded assets" still on the ships offshore "because he was not able to maintain adequate communications with them" by radio.

Two days after D-Day, Marines looked for armed Cubans believed to be in the St. George's area of Grenada. For lack of hard intelligence on the Cubans' whereabouts, a Marine commander looked with suspicion on Fort Adolphus because it was flying an "unknown type" of flag.

"The company commander considered using preparation fires to soften what he believed to be a possible Cuban stronghold," the report said. "This consideration was reversed and prep fires were not used. This decision not to precede the attack with preparation fires was sound because, as it turned out, Fort Adolphus was the Venezuelan Embassy."

The report said the Cuban commander was not incompetent, but had not had time to prepare his defenses before the United States invaded the island and thus, with minor exceptions, "was forced to conduct a purely static defense. Given more time, the enemy would have been much better prepared."