Three weeks of battle

Sunday saw an end to a round of fighting in Lebanon which was remarkable for having involved the US Marines. For the moment at least, the Marines and their French, Italian, and British colleagues among the ''multinational'' peacekeepers in Lebanon are out of the line of fire.

The question is whether anything else was accomplished.

Yes, it did settle one other thing. The Druze militiamen up on the mountain above the internationals were denied a military linkup with the Shiite Muslim militia in the southern wards of Beirut itself.

If the linkup had been achieved, a possible further consequence could have been the collapse of the government of Amin Gemayel and of the newly formed and American-trained Lebanese Army.

Because the linkup was prevented by counterbattery fire from the Marine positions along the coast and from US men-of-war offshore, the government of Mr. Gemayel and the Lebanese Army remain pieces on the chessboard of the Lebanon situation.

But the other side of the arrangement is that the Druze and Shiite factions in Lebanon politics are promised a larger voice in the politics and policies of the new Lebanese government. It is supposed to reflect the fact that the Maronite Christians are a minority of the population.

The next step is the effort to put into operation a remodeled government structure more adequately responsive to the wishes of the Muslim majority.

That means that the agreement, signed on May 17, that the Gemayel regime worked out with Israel, under American tutelage, is now out of date. It was achieved by a regime dominated by that Maronite Christian faction that has been a de facto ally and client of Israel for years. Other Maronites objected to the deal with Israel, as did most of the Muslim majority.

So if the truce holds, and if it is followed by a more broadly based government in Beirut, we will be back to square one so far as a peace between Israel and Lebanon is concerned. No government reflecting the inclinations of the entire Lebanese community could accept the agreement that Mr. Gemayel originally accepted.

So, the Druzes and the Shiites failed to get their maximum objective in three weeks of fighting, which, presumably, was the overthrow of the Gemayel faction and capture of the official government of Lebanon, but they did get their minimum objective, which was a larger share in the politics and policies of their country.

That of course means, in turn, that Syria will gain in influence with the Lebanese government.

Before the fighting the Gemayel regime made a peace with Israel, which, if implemented, would have been to the disadvantage of Syria. It would have given Israel the same military security on its northern flank with Lebanon which it now enjoys on its southern flank with Egypt. It would have meant that Israel, instead of having three actively hostile neighbors as it did before the peace with Egypt, would end up with only the one narrow hostile front with Syria.

In other words, Israel's invasion of Lebanon has still failed to win for Israel its main purpose in the invasion, which was peace and access to the markets of Lebanon.

Overall, Israel is worse off now than before it launched the invasion.

There had been 11 months of quiet along the Lebanon front before the invasion. The Palestinians were being held in check by American influence and by the possibility that they might have more to gain from negotiation than from more war. Several political factions in Lebanon were sympathetic to Israel. Security and access to the markets of Lebanon were possible under pre-invasion conditions. Syria was a minor factor and Soviet influence was negligible.

Now the prospect of peace and access to the outside world through Lebanon has vanished. Syria is a major factor, having been the sponsor and arms supplier to the Druze and Shiite factions, which have won a larger voice in Lebanese affairs. PLO troops are back with the Syrians. And the Soviets, who rearmed the Syrians, are back in the Middle East as a factor of weight.

The presence of the Marines prevented the Druze and Shiite factions from gaining decisive control of the government of Lebanon. But it has not given Israel a better position than it enjoyed before it invaded Lebanon.