The Social Democratic Party of Germany (Sozialdemokratische Partei Deutschlands). The party was founded in 1875 and the strongest party in the Reichstag until 1932.The Social Democratic Party of Germany (Sozialdemokratische Partei Deutschlands). The party was founded in 1875 and the strongest party in the Reichstag until 1932.The Social Democratic Party of Germany (Sozialdemokratische Partei Deutschlands). The party was founded in 1875 and the strongest party in the Reichstag until 1932.The Social Democratic Party of Germany (Sozialdemokratische Partei Deutschlands). The party was founded in 1875 and the strongest party in the Reichstag until 1932.