Blücher spent most of the months after commissioning in fitting-out and improvement work and was judged ready for action only on 5 April 1940. She then sailed in Operation Weserübung four days later, carrying the forces intended to seize Oslo. A British submarine missed the group, but a Norwegian patrol boat transmitted an alarm before being attacked, and shore batteries fired warning rounds as the force advanced. German ships initially withheld fire because the operation depended on concealment and a claim that Germany had come to protect Norway from Britain. Continuing into the fjord after surprise was lost converted a delicate political deception into a direct assault against prepared coastal defenses.
Notable Point · 38:40-42:18
Blücher entered Weserübung barely ready and without surprise
Declared ready only four days before the invasion, Blücher pressed toward Oslo after patrol craft and shore batteries had already raised the alarm.