He began questioning the Vietnam War during an archaeology expedition in Egypt, where he learned about the country's colonial history under British rule.
Stapp participated in a sit-in on Hiroshima Day in 1965, where he was arrested for disorderly conduct and accused police of throwing tear gas into locked vans of arrestees.
[11] Private Paul Ilg, who attended the trial, accused a lieutenant of perjury for claiming to have initiated the original order.
Youth Against War and Fascism sent several sympathizers to the trial, and Stapp began spending time with one of the activists, Deirdre Griswold.
When Stapp took a leave in late 1967, he married Griswold and they began forming the American Servicemen's Union.
Stapp advocated for a right to refuse orders, racial equality, freedom of association, a right to trial by jury, election of officers, and a federal minimum wage.
[15] When Esquire magazine published a profile in August 1968 on Stapp and his organizing activity, the article was banned from the base exchange.
With the support of the American Civil Liberties Union's Seattle office, Stapp filed a lawsuit in response.
[16] Stapp began organizing with the Workers World Party and the affiliated Youth Against War and Fascism.