The invasion of Grenada 27 months ago achieved its objectives of freeing American students with little loss of life or damage to the island but exposed shortcomings in the U.S. military that must be corrected if the United States is to operate successfully in "low-intensity" third-world conflicts.

This is a widely held view among professional military officers familiar with the Grenada foul-ups and among lawmakers drafting legislation designed to centralize military responsibility and clear some of the underbrush between Washington and the commander on the scene in remote military operations.

"We've got to get over the idea that more is better when it comes to deciding how many different military outfits should be used in operations like this," said one Pentagon executive in faulting the four-service approach used during the Iran rescue mission of 1980 and the Grenada invasion of Oct. 25-Nov. 2, 1983, code named Operation Urgent Fury.

The Joint Chiefs of Staff for the Grenada operation employed Marines who were en route to Lebanon; Army 82nd Airborne paratroopers and Rangers, and the Navy aircraft carrier USS Independence, its escorting warships and Seal special forces. Air Force warning and fighter aircraft stood guard to take on the Cuban military if it moved toward the island.

In a postoperation evaluation, the Joint Chiefs of Staff said that such overwhelming forces were needed to seize two airfields quickly without resorting to indiscriminate firepower and to rescue American students and the Grenadian governor general before the estimated 700 Cubans on the islands could kill them or hold them hostage. American casualties were 19 killed and 115 wounded.

A staff report of the Senate Armed Services Committee, while criticizing the command and control structure of today's military, said that "the principal missions -- the rescue of the American medical students, the restoration of democracy and the expulsion of Cuban forces -- were accomplished rapidly and with relatively little loss of life."

However, the Armed Services panel and the Pentagon, in after-action reports, have reported numerous glitches in the operation, including these:

Communication breakdowns. Incompatible radio equipment resulted in Army officers not being able to call in supporting fire from Navy ships. They resorted to ham radios, sent couriers to vessels by helicopter and in one case, according to a Senate Armed Services Committee report, used an AT&T credit card to place a call on a civilian telephone to Fort Bragg, N.C., in the hope of having a request relayed.

The Senate report called this communications gap "unacceptable" and asked, "Is it not possible to buy equipment that is compatible rather than having to improvise and concoct cumbersome bureaucracies so that the services can talk to one another?"

Advance planning. The military's after-action report on Operation Urgent Fury acknowledged that troops were sent into hostile territory without good maps, accurate intelligence, functional radios or protective artillery.

Logistical failures. Troops did not have needed vehicles, long-range communications gear and heavy antiarmor weapons immediately after they landed, according to the Senate report. The supply pipeline was "cumbersome," requiring the Army to send messengers to Fort Bragg to order supplies, it said. The first delivery took eight days.

All-service involvement. The Joint Chiefs of Staff rejected the Atlantic Fleet's initial plan, later withdrawn, to use only Navy and Marine forces rather than add Army and Air Force outfits, according to the military's after-action report.

A report written by William S. Lind, a former Senate aide who founded the Military Reform Institute, concluded that a "pie-dividing contest" among the services allowed a relatively small number of Cuban defenders to "form and maintain a fairly effective defense."

High-ranking military officers have said the mission would have been smoother had only and Navy and Marines been involved, and the Senate Armed Services Committee report cited interservice tensions when Marines assigned to the northern half of the island staged an amphibious landing on the southern portion of Grenada occupied by the Army.

Failure to suppress enemy defenses before helicopter attacks exposed the helicopters to heavy losses, according to Marine analyses. Nine of the 107 helicopters used in the invasion were destroyed or badly damaged.

The flaws exposed during Operation Urgent Fury have prompted a number of influential lawmakers to draft legislation to force reforms on the way the Pentagon makes decisions and commands the battlefield. Sponsors of this legislation argue that losses would be disastrous against a formidable foe if the breakdowns on Grenada should recur.

"We paid a higher price than we should have paid," Rep. Dan Daniel (D-Va.), a member of the House Armed Services Committee, said yesterday. He and Sen. William S. Cohen (R-Maine) are drafting legislation to strengthen Special Forces of the military in the belief they hold the best promise for what the Pentagon calls "low-intensity warfare."

Daniel, on the basis of the Armed Services Committee investigation, said yesterday that the Joint Chiefs of Staff were guilty of mismatching forces and missions. "You don't drop Rangers into a daylight drop zone; you don't send Seals out to make lightning raids in daylight when they're trained to operate at night; you don't send in lightly armed forces without them being able to hide or get the support of massive firepower," he said.

"We lost some people we shouldn't have," said Sen. Strom Thurmond (R-S.C.), a reserve Army major general and second-ranking Republican on the Senate Armed Services Committee. He decried communication failures on the ground, lack of coordination and Washington interference with the commander on the scene.

Sen. Gary Hart (D-Colo.) said yesterday that the big lesson of Grenada is the need for the nation's military leaders to restructure more of their forces to the "most likely threat" -- brushfire operations like Grenada -- rather than concentrate so heavily on fighting an all-out war with the Soviet Union.

"We're trying to fix it," said Sen. Carl Levin (D-Mich.), a member of the Armed Services Committee, in referring to a military command system which, he contended, Grenada showed was broken. He said the remedies are in the military reform bill now being marked up by the Armed Services Committee. "The gaps in our intelligence could have been serious," he said, such as not knowing that Americans were located on two campuses rather than one. He said if the Cubans had seized the unknown, second group, "we could have had another hostage situation like the one in Iran."

Chairman Barry Goldwater (R-Ariz.) of the Senate Armed Services Committee and Sen. Sam Nunn (D-Ga.), its ranking Democrat, have cited these and other shortcomings of the Grenada operation in pushing ahead with legislation to overhaul the Joint Chiefs of Staff, principally by giving its chairman more power, and delegating more power to theater commanders.