In the year since Islamic militants seized the American hostages, Iran's isolation has grown steadily. But it took the war with Iraq to drive home the point in Tehran and give the country's Moslem revolutionary leaders an excuse to free the captives without loss of face.

Iraq's invasion, forcing the Iranian leadership to look abroad for support, gave the ruling mullahs a hard lesson in getting along with the rest of the world. Without that lesson, the hostages very likely would not have figured in the tense election-eve drama surrounding efforts to get them released.

Indeed, in the first weeks of the autumn war with Iraq, the hostages were all but forgotten in the fervor of repelling the invaders and the Byzantine intricacies of the revolution's continuing power struggle. But as the war stretched out -- and Iran's tactics call for protracted conflict against the smaller, less populated enemy -- Tehran's dependence on spare parts for its U.S.-made arsenal grew. So, too, did Iran's desire to tap billions of dollars of assets in the United States now frozen in reprisal, for the hostages' seizure.

In retrospect, the war thus represented a much-needed pretext for ending a situation whose usefulness arguably ended some months ago. But such was the stigma of even mentioning the hostages before now that few Iranian politicians dared grasp the nettle.

Most of the dividends from the embassy takeover were achieved early on. The radical students gambled that by seizing the diplomats they could unseat moderate Prime Minister Mehdi Bazargan and reinvigorate a slowing revolution.

They succeeded for a time. Extremists of the left and right ganged up to eliminate the pro-Western moderates, often thanks to documents left in embassy files. In the process, the radicals sacrificed access to American military and civilian spares. But such was the enthusiasm for Islamic revolution and small-is-beautiful economics that belt-tightening was hailed as proof of zeal.

Today the much-vilified Army, long suspect in revolutionary eyes for its pampered-pet loyalty to the late shah, is exhorted to fight and die on official radio not in Islamic, but rather in Persian national terms.

Against this background, President Abol Hassan Bani-Sadr has sought to enhance his much-tarnished image by showing up unexpectedly in uniform at the front lines.

But even were his current swash-buckling to succeed and resuscitate political fortunes that appeared in late summer to have touched rock bottom, Bani-Sadr could well be swept aside by a rehabilitated military establishment.

Still, a year ago Bani-Sadr was a lonely figure in condemning the embassy takeover and calling for the hostages' release. Today that view seemingly has won over the majority and -- and all importantly -- even Ayatollah Ruhollah Khomeini himself.

In the meantime, Iran's isolation has grown and arguably the revolution has waned. The isolation came home to plague the leadership when the war with Iraq revealed precious few friends willing to help. Aside from a weakened Syria and a Libya not yet forgiven for allegedly killing a Lebanese Shiite Moslem leader, the only other major parties willing to provide help in one form or another were the United States and the Soviet Union -- the two "great Satans" in Khomeini's lexicon.

Gone, seemingly forever, is the Third World radical chorus of the admirers entranced by the David and Goliath aspects of the struggle against the United States and Iran's promise of rejecting Western materialism in favor of its own, albeit modernized, vision of Persian roots.

Khomeini's threats of exporting the Islamic revolution to the vulnerable Arab states along the Persian Gulf, where Shiite minorities could destabilize their Sunni Moslem rulers, fall on increasingly deaf ears these days, at least among that portion of the population educated and powerful enough to air its views.

American warships patrol inside the gulf and AWACS early-warning radar aircraft are readily accepted by a Saudi Arabia that less than a year ago was visibly unresponsive to such American protection and talking of cozying up to the Soviets.

Iranian radicals can perhaps be forgiven for charging that the United States put Iraq up to invading Iran. Certainly for the time being the United States and the West in general appear to be the principal beneficiaries of the war.

But such easy talk forgets that even were the hostages not at stake, the United States has a real interest in preventing the dismemberment of Iran, which despite Baghdad's disclaimers is thought to be a likely Iraqi war aim.

Dismemberment of Iran is much more likely to lead to meaningful Soviet or leftist inroads than the threat of the country's small, well disciplined and increasingly well positioned left. The Majaheddin-e-Khalq, or the Islamic Marxists the shah loved to denounce, could, in the words of a mullah, "take power in five minutes, but they'd lose it in 10." For such is the power of the much-criticized mullahs, the strength of their party organization and Khomeini's undisputed authority.

With the hostages eventually out of the way, the Islamic Republican Party and its lay protagonists will have cleared the decks for the titantic battle that each side is preparing silently for the day when Khomeini, now 80, is no longer around.

What seems likely is that Iran and its revolution seem condemned to a long period of confusion and instability. So far Tehran has kept its non-Persian peoples in line, even the Arabs of oil-producing Khuzestan, the scene of Iraq's invasion.

The central government has paid a bloody price suppressing the Kurds. But if nothing else, keeping the country together may stand as one of the regime's principal accomplishments of the past year. It was mightly helped by an Iraq that had forgotten that cardinal rule: never invade a revolution.