The text in the box says :
"The Navy is here!" Such was the historic greeting given to 300 British merchant seaman present in the German supply ship Altmark when a naval party from the destroyer HMS Cossack boarded the Altmark in Norway on the night of 16th February 1940 in World War 2. The Altmark, which had on board British seamen captured from ships sunk by the German battleship Graf Spee, had tried to get back to Germany. She was intercepted by the Cossack and took shelter in the fiord. The Cossack followed her in and, by superb seamanship in the narrow icy waters, her commander - Captain Vian - ran the Cossack alongside and boarded the German ship. After a hand-to-hand fight with fixed bayonets, the British sailors released the imprisoned seamen and brought them home in triumph. It was an adventure that Captain Marriat would have revelled in for one of his robust sea novels.
All good clean stuff!