If the documents impugning President Bush's service in the Air National Guard turn out to be a forgery [front page, Sept. 10], it won't be the first time such mischief has figured in a presidential election. In fact, the current episode is eerily reminiscent of one that probably determined the outcome of the election of 1880.

That year Republican Rep. James A. Garfield was locked in a close race with a Democratic ticket led by Gen. Winfield Scott Hancock. The economy was in distress, and a contentious issue was whether the importation of low-paid labor from China was contributing to joblessness on the part of native-born Americans. Call it in-sourcing.

Two weeks before the election, an obscure New York City journal, Truth, published a letter purportedly from Garfield to one H.L. Morey, a New England industrialist. In the letter -- marked "Personal and Confidential" -- Garfield expressed the view that the importation of Chinese labor was appropriate, because "companys [sic] have the right to buy labor where they can get it cheapest."

The Morey letter caused an immediate sensation. No one knew where it had come from; the editor of Truth claimed to have found it on his desk. At Democratic headquarters, members of the National Committee examined the letter and pronounced it genuine. Garfield just as quickly denounced it as a forgery.

Handwriting experts were summoned and in a matter of days had concluded that the letter was a clumsy forgery. Two misspellings -- "companys" and "employes [sic]" -- tended to confirm their findings, as did the fact that the envelope bore a stamp rather than Garfield's hand frank. Finally, the Republicans were able to satisfy the country that no person named H.L. Morey had recently lived in Lynn, Mass.

By Election Day it was accepted that the Morey letter was a forgery. Even Democrats were embarrassed; a pro-Hancock paper, the New York Sun, editorialized that "if a party requires such infamous aids . . . [it] deserves to perish."

And perish it did. On Nov. 2, 1880, Garfield was elected president by a popular plurality of only 10,000 votes. Most people thought the Morey letter had made the difference.

JOHN M. TAYLOR

McLean

The writer is a historian whose books include a 1970 biography, "Garfield of Ohio."