Vian boards Altmark inside a Norwegian fjord

British forces searched for Altmark while the German tanker carried merchant sailors captured by Admiral Graf Spee through neutral Norwegian waters. Norwegian inspections had not freed the prisoners, leaving the Royal Navy unable to prove the violation without boarding. Vian forced Cossack into Jossingfjord, pushed past Norwegian opposition, and closed despite Altmark's searchlights and attempt to crush the destroyer against the fjord wall. Boarding parties crossed by ropes and grappling lines before overwhelming resistance and releasing the captives. The operation deliberately stopped short of taking Altmark as a prize, preserving enough political and moral justification for Britain to defend the breach of Norwegian neutrality.