Born in Garham, in Lower Bavaria, Plettl completed an apprenticeship as a ladies' tailor.
From 1912, he was instead chair of the union's South West German district.
[1][2] Plettl joined the Social Democratic Party of Germany, and in 1916, he won a seat on the municipal council in Frankfurt.
[1][2] In 1933, the unions were banned by the Nazis, and Plettl was arrested and imprisoned, being moved to Spandau Prison after a few weeks.
[1][2] Plettl remained in the United States after World War II, and died in Florida, in 1963.