When Ariel (Arik) Sharon, the architect of Israel's massive invasion of Lebanon, was waiting in the wings to become defense minister last year and Prime Minister Menachem Begin was asked why he was balking at the appointment, Begin reportedly answered that it would only be a matter of time before Sharon sent tanks to ring the prime minister's office.

The barb was quickly disowned, but the denials had a hollow ring. As former defense minister Ezer Weizman wrote in his memoirs, "Begin really believes Sharon capable of doing such a thing."

Now, however, Sharon, who long has been described in a popular Israeli maxim as "a war looking for a place to happen," appears to have been unleashed by Begin and given a completely free hand in mapping out a strategy for crushing the Palestine Liberation Organization in Lebanon and ending Syrian dominance in that war-shattered country.

Just how Sharon convinced a once-reluctant Cabinet to go for broke in Lebanon and confront the Syrians head-on is far from clear. By all accounts, a Cabinet majority was firm in its resolve following an anguished 6 1/2-hour meeting Monday night to limit Israel's objectives to creating a 25-mile "artillery free" zone in southern Lebanon and crippling the PLO's capacity to attack Israeli civilian settlements in the northern Galilee.

But however Sharon managed to turn the tide of opinion in the Cabinet, it safely can be said that the force of his personality was a factor.

The barrel-chested, swashbuckling, 54-year-old war hero always has evoked emotionally charged responses from his followers and detractors. But in the end, he usually gets his way.

To his admirers, Sharon is one of Israel's most brilliant and inspiring field commanders--unconventional, perhaps, but brave beyond question and not afraid to put his own career on the line if it means engaging the enemy. To his critics, Sharon is a petulant, undisciplined and insubordinate militarist whose enormous personal ambition skates at the edge of psychosis.

Wrote Weizman: "Striding through life, he tends to leave behind him a wide swath of bitter enemies, disappointed sympathizers and fervent admirers . . . . But political life has different values. Sharon has lost sight of the distinction between his own personal good and the good of the state."

Mordechai Gur, a former Army chief-of-staff, once said, "Sharon is a man who is motivated by power and believes in using it to solve problems. So long as he was under the control of moderate commanders and ministers of defense, it was possible to contain him. But one should not place the defense portfolio in the hands of a man like Arik."

Sharon is no stranger to controversy.

Born in what was then the British mandate of Palestine, he joined a Jewish paramilitary youth organization at the age of 14 and later fought in the Jewish underground army, the Hagana, in which he was wounded in an unsuccessful attempt to capture a Jordanian police fortress in Israel's 1948 war of independence.

At the age of 22, he was appointed to head elite commando units that developed the techniques of behind-the-lines raids and other unconventional fighting tactics that became his hallmark.

His Unit 101, created in Sharon's unruly image, repeatedly struck across the Jordanian border in retaliation for Palestinian guerrilla attacks, and on one such raid, in the village of Qibiya in 1953, killed 69 civilians, half of them women and children, when the unit blew up Arab houses.

During the 1956 Sinai campaign, Sharon disobeyed orders and dropped his paratroops in an operation that cost 38 Israeli dead and 120 wounded. Moshe Dayan wrote in his memoirs that Sharon was saved from a court-martial only because of the Israeli doctrine that commanders are punished for doing too little, not for doing too much.

After the 1967 Six Day War, Sharon subdued the occupied Gaza Strip with a tough--some called it brutal--policy of blowing up houses, bulldozing large tracts of refugee camps and handing out harsh collective punishment for terrorist acts.

In the 1973 war, Sharon led a crossing into Egypt that, while described as reckless at the time by military strategists, later was credited with shortening the war.

As agriculture minister in the Likud government's first four-year term, Sharon single-handedly engineered Israel's aggressive settlement policy in the occupied West Bank, building scores of new Jewish communities in what he openly acknowledged was an attempt to "establish facts on the ground" to forestall any compromise by which Israel would have to withdraw from the territory.

In April 1980, Sharon provoked a controversy with his harsh criticism of Israeli television news coverage of his policies in occupied territories when he shouted, "You're a gang of terrorists!" at a camera crew filming a Gaza Strip protest. "I fought terrorists successfully when I was in the Army and I'll fight you successfully."

The outburst prompted enraged reaction in the Israeli press, with the Jerusalem Post labeling Sharon in an editorial as "a clear and present danger to Israeli liberties."