Joseph joined the movement at the age of sixteen. He went on a hahshara in Kolozsvár (Cluj) and prepared for aliya but the plan was not carried out. In that town he worked in a metal factory and met young Hungarians, communists and socialists who worked for the underground. Joseph also joined the anti-fascist movement in 1941. He moved to Budapest and joined the “Hashomer Hatzair” activities. He maintained contact with the leftwing workers and engaged, among other things, in collecting clothes and food for the political detainees. In October 1943 Joseph was enlisted in a forced labor unit. While serving there, he was arrested and interrogated about his relations with the leftwing groups and his activities in “Hashomer Hatzair” but was released and taken back to the labor unit.
In October 1944 Joseph escaped with the help of the movement and joined its underground activities. He was ordered to maintain his contacts with the Hungarian communist and anti-fascist underground and he opened a new channel of cooperation between the two parties. The “Hashomer Hatzair” people provided the Hungarian underground activists with forged documents, food and clothes while they mainly helped find hiding places. Joseph Meir operated in the suburbs of the capital, in Købánya and Újpest and organized the desertion of a group of Hungarian officers and soldiers who gave him various weapons. He saved both groups of Jews and single ones while wearing an Arrow Cross uniform.
After the liberation Joseph joined the Political Department of the Hungarian Ministry of the Interior where he localized Nazi criminals, Arrow Cross men and officers of the forced labor camps. Later Joseph was appointed commander of the Hagana that was set up under the communist regime to protect the Jews.
Joseph made aliya in 1948. He took part in the War of Independence within the framework of the Palmah and, when he was demobilized, he joined Kibbutz Ga’aton. Joseph held various positions in his kibbutz, in public institutions and in the Kibbutz Artzi.