On March 5, James R. Schlesinger, the Secretary of Energy, went on nationwide television and issued a dire warning to the nation.

Schlesinger told CBS' "Face the Nation" that if the coal strike continued much longer, by the end of March, "We may be looking at as much as a million . . . people unemployed in the affected region of the Middle West,"

If the shutdown lasted through late April, he predicted, "We would be facing up to 3.5 million . . . unemployed because of the . . . lack of power . . . And that would have ripple effects throughout the economy"

On March 24, United Mine Workers members voted to ratify a proposed contract settlement and end the long strike, which lasted a record 109 days.

The toll: While the strike had harsh effects in a few hard-hit areas, it actually had very little impact on the overall economy. The total number of layoffs never, got much above 25,000 workers - out of a work force of 99 million.

By any valid measure, the administration's miscalculation was a massive one - far more serious than usually is expected in standard economic forecasts and assessments.

It also was costly. Not only did it prompt fears that later proved unfounded, it also created pressure for the White House to seek a Taft-Hartley injunction. Some say it may even have exacerbated the strike.

Why were the administration's estimates so far off the mark? Was the White House forecasting machinery simply that inadequate? Or, did officials bloat the figures some to help "justify? their bid for a back-to-work order?

Talks with some of the officials involved in the administration's strike forecasting effort showed that, through a combination of mishaps and internal pressures, the fiasco actually may be attributable to some of each.

There were these developments:

The "disaster" forecasts of 1 million to 3.5 million unemployed were actually put together by a sideline staff in the Energy Department, and picked up by Schlesinger by chance.

While House economists, as well as others in the Energy Department, considered the forecasts grossly exaggerated, but never formally spoke out against them - even though they clearly conflicted with most other projections.

Once Schlesinger had issued the doomsday warnings publicly, there was pressure from the White House "political side" to continue to portray the strike in the worst terms - in part to maintain pressure for the two sides to negotiate.

Efforts by some administration economists to correct the forecasts went largely ignored, according to key officials. "Nobody wanted to do anything that might hurt chances for the injunction," one insider said.

Much to its own amazement, the administration found itself able to move coal supplies more easily than expected once Western coal production resumed and non-union miners went back to work.

"We really were surprised," says a White House official who was involved in the strike handling effort. "The economy was able to handle this a lot better than we thought."

According to officials, the forecasting mistakes - and the doomsday economic projections - actually didn't begin until relatively late in the game.

Initial predictions - put together late last autumn by a joint White House-Energy-Labor task force - showed that the strike most likely would have only a marginal impact. Supplies were judged big enough to last "almost indefinitely."

The trouble began when the Energy Department allowed two task forces to make separate projections - one in the agency's main economic section and a second under the Federal Energy Regulatory Commission.

While the first group compiled projections that seemed in line with other forecasts, the second factored in estimates from state regulatory bodies, which omitted any possibility that higher prices might bring in more coal.

On the weekend of the "Face the Nation" telecast, Schlesinger tok the projections from the second group and used them, apparently not knowing they were faulty, first to brief the president and then on the TV program.

The reactions of officials inside the administration was mixed. At least one key economic agency protested, insisting that there really was no crisis at hand. Other officials remained silent. In any case, there was no public correction.

On March 7, the administration filed its application for a temporary restraining order against the miners under the Taft-Hartley Act, with the supporting documents needed to "justify" the economic danger.

The affidavits filed by the Justice Department, Schlesinger and other key economic officials all used the Energy Department estimates - that the strike could result in 1 million layoffs by late March and "3.5 million in April."

The only agency not to support that projections was the Council on Wage and Price Stability. Reportedly, council officials flatly refused a request for supporting data, on grounds that an injunction wasn't justified. The administration did not make the council's refusal public.

Worst case estimates by outside experts were less pessimistic. Otto Eckstein, head of Data Resources, Inc., the economic consulting firm, predicted the strike could result in 750,000 layoffs by late March and 2 million by late April, but hedged his bets somewhat.

But Alan Greenspan, former Ford administration chief economist, cautioned that the impact might be less serious than was being forecast, because the economy might prove more able to adapt to the shutdowns than some were predicting.

Greenspan was right. When the Western coalfields resumed production - after the injunction was granted - coal began coming through in significant volume, and supplies were maintained.

From a low of 300,000 tons a week, deliveries began rising, first to 800,000 tons a week and then, by a final week for the strike, to 1.4 million tons, close to the 2 million ton mark experts say is "normal."

Near the end of the strike, federal judge Aubrey Robinson refused to continue the administration's Taft-Hartley injunction on grounds that the government had failed to show an economic danger from the strike.

A department of Energy spokesman said yesterday his agency was "absolutely delighted" that the forecasts were wrong because it would have been disastrous if they had turned out to be accurate.

The question is, was the danger really ever there in the first place?