Why did the postwar Social Democratic Party of Germany in West Germany oppose rearmament and Western military alliances?

In the early postwar period, the Social Democratic Party of Germany (SPD) opposed rearmament and integration into Western military alliances primarily due to its commitment to German reunification and a desire to avoid further entrenchment of the country's division.123

Under the leadership of Kurt Schumacher, the party maintained a stance that prioritized national unity over the integration policies pursued by Chancellor Konrad Adenauer. The SPD leadership, which drew political legitimacy from its historical opposition to Nazism, adhered to a strictly orthodox Marxism during these years and vehemently rejected the country's inclusion in Western defense systems, such as NATO.132

This opposition was rooted in the fear that aligning West Germany with the West would solidify the partition of Germany and hinder the possibility of a unified state. It was not until the Bad Godesberg Resolution in 1959 that the party abandoned its doctrinaire approach, moving toward a more moderate, reformist platform that eventually broadened its appeal to the middle class.132