year or so ago a newspaper published a patriotic quatrain by a shopkeeper in the Falkland Islands:

There will always be a Falklands,

With peace and lib-er-ty,

That's why our Navy fought and died,

To keep our dear land free.

This doggerel celebrated a long forgotten naval engagement in the South Atlantic in World War I. Now the British Navy again has been dispatched, this time by Prime Minister Margaret Thatcher, to keep the "dear land free." But foreign military analysts are perplexed as to how the objective can be achieved and they wonder if the British commanders are any less perplexed.

It is taken for granted here that the first British move will be to retake the lightly defended island of South Georgia, a desolate rock covered with glaciers. Its garrison of 300 to 500 Argentine troops is considered by both Argentine and foreign military analysts to be vulnerable to a British assault. The probable landing beach is at Gryvteken on Cumberland Bay, the only habitation on the island.

But then what?

The Falkland Islands, the main object of this exercise, lie 800 miles to the northwest. They are occupied by as many as 10,000 Argentine troops who have had three weeks to build extensive fortifications.

The magazine Somos, closely identified with the military junta here, published this week a detailed map of the islands' defenses. It showed underwater mines strung around the entire island group. The Argentines were extending the airfield at Port Stanley and constructing two new airfields to handle both fighters and C130 transports. They have laid inland mines and tank obstructions and mined landing beaches.

Missile and antiaircraft batteries have been installed. Artillery has been emplaced on the high ground overlooking the landing sites. The whole area can be reached by land-based fighters and bombers located as near as 400 miles.

Military analysts believe a frontal assault on these islands by the British would be a suicidal venture. If not that, what remains?

One theory is that the British fleet could steam near the Argentine coast to search out Argentina's Navy. But, according to one high-ranking Western analyst, that move could also prove suicidal.

"Do not underestimate Argentine air power," he said. "These pilots are good. They are experienced and they are . . . almost in a kamikaze mood. If the British bring their carriers within range, I can see the scenario now. The Argentines will send out two flights of A4s the American Skyhawk fighter bomber , eight planes to a flight. They will be loaded with iron bombs. They will say, 'Okay, 10 of us won't make it but the other six are going to get a carrier.' If that were to happen, Maggie Thatcher is in deep trouble and so is the fleet. They only have three carriers in their whole Navy."

If this analysis is correct and the British fleet chooses to remain out of range of the air bases both on the coast and on the Falklands, it will have very limited options.

One speculation of the analysts is that an air strip can be constructed on South Georgia Island to accommodate bombers and Harrier fighters. It could be used, theoretically, for raids on the Falklands and for transporting British paratroops for an airdrop.

But airdrops, like all military operations at this time of year, are hostages to the weather. When the first British vessels appeared near South Georgia on Friday, they were met with 40-foot seas and winds of hurricane force. Neither paratroops nor small landing craft can operate in such weather.

There is also talk in London, according to published reports, that in the end the British may attempt a blockade of the Falklands and possibly of certain Argentine ports, such as Puerto Belgrano, 800 miles northwest of the islands.

How that can be accomplished is, again, unclear. British submarines supposedly already have established a shipping blockade in the 200-mile radius around the islands. But it is ineffectual because the Argentines are resupplying the islands with an "air bridge" of C130s and Boeing 737s flying out of coastal ports.

To stop the air resupply, the British would require a stronger force of aircraft than they now have, according to the analysts here. The two carriers in their South Atlantic fleet have only 20 Harrier vertical-takeoff jets, which have a limited combat range. The Argentines, on the other hand, have 82 A4 Skyhawks, plus squadrons of Mirage and Dagger interceptors.

In this situation, an American observer said, "Maggie Thatcher needs blood for her constituency and she's likely to get it in South Georgia. After that, I have no idea what comes next. The British fleet could sit out in the South Atlantic for a long time, waiting for the diplomats to work something out."