HELENA, Mont., May 2 — When Steve Milch found out recently that his great-grandfather, an immigrant from Bavaria, had been convicted of sedition in Montana during World War I, he was taken aback. It was something no one in the family had ever talked about.

For the past 88 years, a lot of secrets have been kept in Montana families, especially those of German descent, about a flurry of wartime sedition prosecutions in 1918, when public sentiment against Germany was at a feverish pitch.

Seventy-nine Montanans were convicted under the state law, considered among the harshest in the country, for speaking out in ways deemed critical of the United States. In one instance, a traveling wine and brandy salesman was sentenced to 7 to 20 years in prison for calling wartime food regulations a “big joke.”

But the silence — and for some families, the shame — has ended. The convictions will be undone on Wednesday when Gov. Brian Schweitzer, a descendant of ethnic Germans who migrated here from Russia in 1909, posthumously pardons 75 men and three women. One man was pardoned shortly after the war.

Forty-one of those convicted, including one woman, went to prison on sentences from 1 to 20 years and paid fines from $200 to $20,000.

“I’m going to say what Gov. Sam Stewart should have said,” Mr. Schweitzer said, referring to the man who signed the sedition legislation into law in 1918. “I’m sorry, forgive me, and God bless America, because we can criticize our government.”

Dozens of relatives of the convicted seditionists will be at the State Capitol to witness the signing of the pardons, with some traveling from as far as Florida. Marie Van Middlesworth, the 90-year-old daughter of one of those convicted, Fay Rumsey, will be coming from Medford, Ore. She was among 12 children put up for adoption when the family farm failed after her father was imprisoned.

Mr. Milch said the official acknowledgment, even after so many years, offered comfort and closure to the families.

“The whole Milch clan is appreciative of making things right,” he said.

The pardon ceremony is a result of a book by Clemens P. Work, director of graduate studies at the University of Montana School of Journalism, called “Darkest Before Dawn: Sedition and Free Speech in the American West” (University of New Mexico Press, 2005). The book chronicled a contentious period in Montana history when people were convicted and jailed for voicing their opinion about the war.

“It was an ugly time,” Mr. Work said.

After reading the book, Jeffrey Renz, a law professor at the University of Montana, asked Mr. Work what he intended to do about the convictions. Mr. Work had no plans, he said, “but I told them in my box of dreams I hoped these people would be exonerated.”

Professor Renz’s students took the project on as part of a criminal law clinic. Some contacted family members of the convicted seditionists, and others researched the law, leading to a petition for pardon being sent to the governor last month.

The sedition law, which made it a crime to say or publish anything “disloyal, profane, violent, scurrilous, contemptuous or abusive” about the government, soldiers or the American flag, was unanimously passed by the Legislature in February 1918. It expired when the war ended, Mr. Work said.

During that time, though Germans were the largest ethnic group in Montana, it was also illegal to speak German, and books written in it were banned. Local groups called third-degree committees were formed to ferret out people not supportive of the war, especially those who did not buy Liberty Bonds.

“They leaned on people to ante up and buy bonds, and if they didn’t, they were disloyal and considered pro-German,” Mr. Work said.

Farida Briner said she was told that a committee showed up at her father’s farm. “They threatened to hang him and tar and feather him,” Ms. Briner said. Her father, Herman Bausch, was taken to town, interrogated and later convicted. He spent two years in prison.

Officials encouraged neighbor to inform on neighbor, and one person’s accusation was often enough for an arrest.

Mr. Milch’s great-grandfather, John Milch, was turned in by an undercover agent named Eberhard Von Waldru, who was working for the prosecutor in Helena, the state capital. Mr. Von Waldru went into a German beer hall and drew out people’s feelings on the war. His testimony was used against Mr. Milch; his brother, Joseph; and six other men. All were convicted, and four went to prison.

John Milch was sentenced to three to six years, but the law had expired by the time he was to begin serving his term. Joseph was fined $1,800.

Steve Milch said that although his family was not aware of the arrest, they did know about the anti-German sentiment of the time.

“There was a story that a mob of people was going around asking Germans to kiss the flag,” Mr. Milch said. “My great-grandfather told them he didn’t kiss anybody’s flag, whether it was American or German.”

Mr. Milch also had another surprise in store. He discovered that the great-grandfather of another lawyer in his firm was the Helena prosecutor who hired Mr. Von Waldru. “His great-grandfather prosecuted my great-grandfather,” Mr. Milch said.

Mr. Work, who was conducting research for the book when the Sept. 11 attacks occurred, said he had found the similarities between 2001 and 1918 to be eerie.

“The hair on the back of my neck stood up,” Mr. Work said. “The rhetoric was so similar, from the demonization of the enemy to saying ‘either you’re with us or against us’ to the hasty passage of laws.”

Twenty-seven states had sedition laws during World War I. Montana’s became the template for a federal law, enacted by Congress later in 1918. More than 30 Montanans were arrested under the federal law, though none were convicted, according to the Montana Sedition Project, which Mr. Work directs.

Mr. Work and other historians believe that the harshness of the Montana law was influenced by the Anaconda Copper Mining Company, which dominated the state economically and viewed the law as a way to deal with labor unrest. Many of those charged with sedition were immigrant laborers.

But blame should also be laid at the feet of Governor Stewart, Mr. Work said.

“In the last 100 days of his term, he commuted 50 sentences, including 13 murderers and 7 rapists,” he said, “but not a single seditionist.”