Historically, many events which seem small at one time, later assume major magnitude, and the question frequently is "what if" things had been handled differently; would this have changed the situation and in what way.

One could ask what would have happened at Normandy had Gen. Dwight D. Eisenhower allowed meteorologists to change the date for D-Day, should the Japanese have headed for the United States mainland after Pearl Harbor, or what about some of the disastrous decisions made by Hitler and Napoleon?

It certainly is of lesser importance, but the recent death of Rosemary Woods, President Nixon's longtime executive secretary, revives for some of us the question we long have wondered about: What difference would it have made to the Nixon presidency had Woods or Bob Finch been made chief of staff to the White House instead of Bob Haldeman?

Like most "what if" questions, we can only speculate on the answer, but we know that each of them was dedicated to the president, each had a distinctively different style, and each was capable.

Haldeman was a power broker who let no one interfere with his position. Finch was a people person and a political policy wonk who was courageous and creative but who might have had difficulty managing a bureaucracy, as proved to be the case when he took over what then was called the Department of Health, Education and Welfare. Nixon once asked Finch to be his vice presidential running mate, but he refused, feeling both were essentially Californians. Woods was a highly intelligent political pragmatist who never hesitated to speak up when she thought the boss was wrong.

The question assumes major importance if one believes that Watergate not only disgraced a president, but it changed American politics and weakened the power of the presidency, perhaps paving the way for the North Vietnamese to break their cease-fire agreement and sweep over South Vietnam. The final decisions on Watergate were made by the president himself, but the influence of one chief of staff or another might have made a difference.

The last rites for Woods, 87, were conducted quietly last week by friends and relatives in Alliance, Ohio. She long had suffered from Alzheimer's disease. The news stories recording her death featured the fact that she had a role in erasing audiotapes she was transcribing during the Watergate investigation. Woods said that four or five minutes of the erasure probably occurred accidentally when she was stretching to answer a telephone while she was transcribing.

Two of the best known executive secretaries to a president were Evelyn Lincoln for John F. Kennedy and Woods for Nixon. Both were highly capable executives, but Lincoln will be best known because of the Kennedy assassination. As the obituaries indicated, Woods probably will be best known for the erasure, not for the many responsibilities she capably undertook during the 25 years she worked for Nixon.

Woods joined Nixon's staff shortly after he was elected to the U.S. Senate, and she remained with him through victory and defeat, through public and private life until he left the White House. During most of Nixon's career until the 1968 campaign, she was in effect, his chief of staff. Finch had that title during the 1960 Nixon campaign against Kennedy, but his concentration was on the political campaign, not office management.

When Nixon was elected president in 1968, his first personnel decision concerned what position Woods would be given. Had she been appointed chief of staff, she would have been the only woman to have been given that position. Woods was his first appointment, and he made her his "personal secretary." That later was changed to "executive secretary," a title now frequently replaced by "executive assistant."

Haldeman was a former advertising executive who was in charge of advance men during the 1960 campaign, and he was the manager of the ill-fated Nixon campaign for governor in 1962. During the 1968 campaign, Haldeman and his college friend John Ehrlichman stayed on the campaign plane with Nixon, and during the final weeks before the election, they began a study of presidential staffs, putting them in the key position to influence the White House staff after Nixon won the election.

During Haldeman's regime, he kept a tight lid on access to the oval office. His style resembled the bureaucracy he opposed; it included a heavy flow of paperwork. He was well organized, but often cold in dealing with people.

Had Woods become chief of staff, her strong people skills would have prevailed. Nixon often described her as "family," and that she really was. She would have been less organized than Haldeman, but she would have been in a position to say "no" to the president when she disagreed. Access to the Oval Office would have been more open than under Haldeman.

On the question of loyalty, it would be hard to exceed Finch, Woods or Haldeman, but on questions of personal agenda, Woods had none while Haldeman sometimes did.

Nixon, Finch, Haldeman and now Woods are deceased. The "what if" speculation is interesting, but it is one where there will be no answer.

Herbert G. Klein is a national fellow at AEI, retired editor-in-chief of Copley Newspapers, and former Nixon White House director of communications.