Wischnewski earned the nickname "Ben Wisch" from West German Chancellor Willy Brandt due to his strong contacts in the Arab world and his engagements with the Algerian National Liberation Front (NLF).

As a close confidant of Brandt's successor, Chancellor Helmut Schmidt, Wischnewski served as a special representative for negotiations during the Red Army Faction (RAF) kidnappings in the "German Autumn" of 1977.

Born in Allenstein, East Prussia (now Olsztyn, Poland), Wischnewski obtained his Abitur degree in Berlin in 1941.

On 1 December 1966, Wischnewski was appointed Federal Minister for Economic Cooperation in the grand coalition cabinet of Chancellor Kurt Georg Kiesinger.

His efforts decisively improved the West German diplomatic relations with numerous Arab and African countries.

When West German business executive Hanns Martin Schleyer was kidnapped by the militant Red Army Faction (RAF) in September, Wischnewski followed the joint RAF and Popular Front for the Liberation of Palestine (PFLP) hijacking of Lufthansa Flight 181 to Mogadishu, Somalia, in October.