The Republican Party has returned, so to speak, to the scene of the crime. Party members assembled this week in San Diego to formalize their selection of Robert J. Dole as their presidential nominee.

Two decades ago, Dole as chairman of the Republican National Committee led his troops to the gates of San Diego, then beat a hasty retreat after we reported that the choice of sites was the result of skulduggery in high places.

Before abandoning San Diego in 1972 for Miami Beach, the man who was scheduled to be nominated again, President Richard M. Nixon, attempted a coverup. We believe it was historic because it turned out to be a dress rehearsal for the blunders, then the crimes, that led to the greatest political scandal in American history -- Watergate.

Here are the intriguing particulars:

In 1972, Nixon wanted to stage his renomination rites in San Diego -- a city that had been witness to his early struggles and triumphs, and had always given him a higher vote than any other comparable metropolis. But the city fathers were oblivious to the honor Nixon wanted to bestow; they voted against even submitting a bid for the convention.

Presidential embraces are not that easily eluded, however. The final date for bids was postponed to give San Diego another chance. GOP bigwigs, including Dole, brought pressure on the city fathers to change their minds.

But alas, the required cash contribution from the host city fell short because local businessmen failed to ante up. At the last minute, International Telephone and Telegraph stepped in with a $400,000 offer to fill the void left by the business community. Not only Nixon's wish but his dignity was thus salvaged.

The donor, mysteriously, was not identified until we printed the inconvenient details. We noted that in 1969 the Justice Department had declared war on a merger wave that had caused 110 of the 500 leading industrial corporations to be swallowed up during the previous six years.

The department issued a public warning against any merger among the top 200 firms. Scarcely had this policy been proclaimed than ITT, then the ninth largest industrial firm, authorized acquisition of 22 domestic and 11 foreign corporations. This resulted in the biggest antitrust case in history.

On the eve of the 1972 election campaign, the Justice Department suddenly announced it had dropped the ITT suits and settled out of court. The political policymakers never bothered to explain this stunning development. They gambled on the news media's limited resources, short attention span, difficulty explaining complicated matters and inability to function when information is cut off.

But sources inside ITT provided us with jigsaw pieces that we were able to put together. The chief piece was an internal memo from ITT's lobbyist-in-chief Dita Beard, tying the $400,000 contribution to the antitrust settlement. The memo ended with a request -- "Please destroy this, huh?" -- that had been ignored.

The Senate Judiciary Committee immediately convened a hit-and-run hearing, not to investigate but to try to refute the scandal. A parade of Justice and ITT witnesses soulfully and indignantly professed innocence before a panel that was on the side of the miscreants. Most of the senators unashamedly revealed themselves, not as judges sternly searching for the truth, but as a rooting section for the accused.

This column asked to appear as witnesses against this righteous breast-beating. With elaborate courtesy, the senators agreed to listen to our testimony after everyone had gone home. So we testified out in the hall in front of the television cameras.

In dozens of particulars, large and small, the tactics used by the Nixon men to wriggle out of Watergate were tested first on ITT. Even the cast of characters was the same -- John Dean, Charles Colson, G. Gordon Liddy, E. Howard Hunt, James McCord, et al. Dean was the stage manager for the ITT coverup, as he was at first for the Watergate coverup.

In one memorable episode, Hunt, in an ill-fitting red wig, paid a late-night call on Dita Beard in a Denver hospital where she had fled to escape the controversy. He persuaded her to return and coached her on what to say.

Nixon's personal defense on Watergate -- that all the crimes were perpetrated by overzealous subordinates acting with good intentions but poor judgment -- also got a dress rehearsal during the ITT siege.

Why, then, did Humpty Dumpty eventually fall and crash into many pieces? There is a fundamental conflict between uniformity and diversity, between politicians and the media, that is built into the American character and system. This has always pitted the ferreter of facts against the mobilizer of opinion.