Andy Stapp, who expressed his opposition to the Vietnam War by joining the Army and proceeding to do a very unmilitary thing — form a union among soldiers that demanded, among other things, the right to elect officers and reject what they viewed as illegal orders — died on Sept. 3 in Manhattan. He was 70.  His wife, Deirdre Griswold, said the cause was complications of a lung infection.  At its peak in the early 1970s, the union that Mr. Stapp formed, the American Servicemen’s Union, claimed to have tens of thousands of members. It issued membership cards, published a newspaper and helped form chapters at military bases, on ships and in Vietnam.  Although the Army never came close to recognizing the union formally, it certainly recognized it as a problem. Mr. Stapp brought colorful idealism to his counterintuitive cause, and the Army did what it could to silence him.  In 1967, while stationed at Fort Sill, in Lawton, Okla., Mr. Stapp twice faced court-martial. The first time was for refusing an order to open his footlocker, which served as his unit’s library of leftist literature. (Officers broke it open with an ax.) He was convicted and served 45 days of hard labor. The second was based on charges that he had left his barracks when he was forbidden to do so. He was acquitted in late 1967.  The Army discharged him the next spring for engaging in what it called subversive activity. Later, through appeal, his discharge status was changed from dishonorable to honorable. Through it all, Mr. Stapp remained popular in the ranks.  “A remarkable aspect of Stapp’s siege of Fort Sill is that the self-proclaimed Communist has never been lynched by his fellow G.I.’s,” Robert Christgau wrote in a 1968 profile of Mr. Stapp in Esquire magazine. “G.I.’s are taught to kill Communists. But they like Stapp. When he won his second court-martial, they cheered. You just don’t win courts-martial.”  The Esquire article was briefly banned from the post exchange at Fort Hood, Tex.  Mr. Stapp’s discharge probably helped his cause. Free of military duty and having gained attention from the news media, he had the time and prominence to organize. He also received support from leftist groups, including, early on, Youth Against War and Fascism, of which Ms. Griswold was a member. Ms. Griswold later became the editor of the Workers World newspaper and ran for president in 1980 as the nominee of the Workers World Party, receiving about 13,000 votes. Serving as his union’s president, Mr. Stapp set up an office in New York and began promoting his cause, sometimes sneaking leaflets and newspapers onto bases for soldiers to distribute.  In 1968, he protested the court-martial of 43 black soldiers at Fort Hood who were accused of refusing to go to Chicago to help quell unrest at the Democratic National Convention that year. In 1969, he helped bring attention to soldiers who faced court-martial for rioting over conditions in the stockade at Fort Dix, N.J.  In 1970, he published his autobiography, “Up Against the Brass.” Reviewing the book in The New York Times, John Leonard wrote: “Mr. Stapp may have the political perceptions and the historical grasp of a kindergarten stormbird — really, all our founding fathers weren’t slave owners and mainland China isn’t exactly lotus-land — but he also has courage. Without his persistence, there would be considerably less civilian concern about Army practices.”  Ms. Griswold, from whom Mr. Stapp had been separated for many years, said she did not think he had expected the Army to recognize the servicemen’s union. But, she added, “I think he believed it would radicalize the people who knew about it.”  Andrew Dean Stapp was born on March 25, 1944, in Philadelphia, to a military nurse who was not married. He spent the first year of his life in an orphanage before being adopted by William and Martha Stapp, an engineer and a homemaker who lived in Merion, Pa., a Philadelphia suburb. He grew up with an older brother, William, who was also adopted.  Mr. Stapp enrolled at Pennsylvania State University in 1963, interested in ancient history and largely apolitical. But his studies of the past sharpened his focus on the present, particularly the developing war in Vietnam.  He began consuming leftist literature and getting arrested at peace rallies. He dropped out of college. While many of his fellow antiwar activists moved to Canada, claimed conscientious-objector status or took other action to avoid serving, Mr. Stapp concluded that he could have the most impact in uniform.  He had burned his draft card in October 1965, which delayed his enlistment. But after convincing his local draft board that his intentions were good, he entered the Army on May 13, 1966.  David Cortright said he was an enlisted soldier opposed to the war when he read the Esquire article about Mr. Stapp in 1968.  “To me it was like a light going off, like a flash of illumination, that maybe I could do the same,” he said in an interview on Thursday. He organized protests against the war and went on to become a professor of peace studies at the University of Notre Dame.  Besides Ms. Griswold, Mr. Stapp’s survivors include their daughter, Katherine Stapp, and a granddaughter. Complete information on his survivors was not immediately available.  The American Servicemen’s Union faded along with the war in the 1970s. By the early 1980s, Mr. Stapp had found a job teaching history at the Hudson School in Hoboken, N.J. He worked there for more than a quarter-century.
As antiwar protester determined to challenge the military from within, Mr. Stapp faced court-martial twice and a discharge for what his superiors deemed subversive activity.