Mr. Assad's big win

Lebanon's Amin Gemayel went to Damascus last week to make his peace with Syria's Hafez Assad. In effect Mr. Gemayel became a client of Syria and accepted Mr. Assad as his overlord.

Thus ended another chapter in the history of the Middle East. It had begun in 1982 when Israel invaded Lebanon with the intention and expectation of becoming the new overlord of Lebanon. The outcome is the opposite of what Israel had intended. The reason for Israel's failure is unusual. This is the first time that Israel's expansion has been checked by Arabs.

Israel has before this been restrained and pushed back, but it was done from Washington, not by Arabs.

The most prominent example was when President Dwight D. Eisenhower insisted on a total Israeli withdrawal from the Sinai peninsula after the 1956 war. Israeli armed forces had quickly taken the entire peninsula. There was no Arab force which could push them back. The only force which could cause them to give up what they had taken in that war was the United States.

That has been the general condition with Israel and its Arab neighbors until this latest chapter in the story. Israel has been physically able to take and hold from the Arabs whatever Washington would allow it to take and hold. There has been no effective Arab resistance to the steady expansion of Israel from its original lodgement along the Palestinian coast.

The first sign of rising Arab ability came in the 1973 war when the Egyptians and Syrians won the first round. They would quite possibly have won a decisive victory had Washington not come to Israel's rescue with a massive airlift of tanks from Germany.

That chapter ended with Washington restraining Israel from capturing an entire Egyptian army at the Suez Canal. The Israelis had that army surrounded. Had they been allowed to capture it and march on to Cairo they probably could have taken that city. Washington said no.

This time the story was different. President Reagan was trying to help the Israelis to attain their main objective i.e., a government in Lebanon friendly to Israel. The main argument for the presence of the US Marines in Lebanon was to sustain the Gemayel regime and the agreement which that regime had made with Israel on May 17 of last year.

If Mr. Reagan's policy for Lebanon had succeeded, Lebanon would, in effect, have become both a political and an economic client of Israel.

The important thing here is that Washington this time was trying to help Israel expand its area of influence into Lebanon. Washington was not restraining Israel. It was encouraging Israel. Even with Washington support, the operation failed.

The feature in this latest chapter of Middle East history has been the skill with which President Assad has deployed the resources available to him. These resources began with his own Syrian Army, which has been improved with Soviet training and the latest Soviet weapons manned by Soviet troops. To this he added control over PLO forces remaining under his command, control over Shiite and Druze militia units in Lebanon, and highly motivated suicide and ''terrorist'' volunteers who, Washington thinks, came mostly from Iran.

Mr. Assad used the PLO, Shiite, and Druze militias against the American-trained Lebanese Army, which collapsed under the pressure. He used clandestine assassins to neutralize Jordan. He encouraged and supported (probably also directed) resistance inside the Israeli military perimeter. This imposed daily casualties on the Israelis, which in turn built resistance inside Israel to the continued occupation of Jordanian territory.

Syria's regular armed forces were never engaged. There was no need. Public opinion in Israel would not have permitted an invasion of Syria when backed by Soviet troops. Even the Israeli Army is no match for the Soviet Army. The Soviet presence also prevented Washington from putting stronger forces into Lebanon. Was the United States going to go to war with the Soviet Union to give Israel control over Lebanon? The Marines were withdrawn, not reinforced.

For skill in the strategy of statecraft there has been nothing comparable to this since Bismarck put modern Germany together over a century ago. President Reagan was outmaneuvered by a master player.