After the Royal Navy sank her, Germany relied entirely on U-boats to sink Allied merchant ships.

[citation needed] Yarrowdale had a single screw, driven by a three-cylinder triple expansion steam engine that was rated at 429 NHP[2] and gave her a speed of 13 knots (24 km/h).

Möwe's commander, KK Nikolaus zu Dohna-Schlodien, saw Yarrowdale's potential for conversion into a commerce raider.

[5] She was disguised as Rena, a cargo ship that had been built in England in 1911 for owners in neutral Norway, and whose size and appearance was similar to Yarrowdale's.

The first was SMS Greif a year earlier, which HMS Alcantara sank before she had a chance to attack any Allied shipping.

By 16 March Leopard was in the Norwegian Sea, where at 1145 hrs the armoured cruiser HMS Achilles and armed boarding steamer Dundee sighted her.

The six Dundee's boarding party were reported missing; presumed captured by Leopard and killed either in the British bombardment or when the German raider sank.

[8] Soon after the action a bottle was found, containing a message purporting to be from a member of Leopard's crew who had thrown it overboard during the engagement.

"[9] After Leopard was sunk, only days into her first patrol, Germany ceased trying to send surface raiders to attack Allied shipping.

The German Navy had resumed unrestricted submarine warfare on 1 February, and after Möwe returned to port on 22 March, Germany relied on U-boats alone to sink Allied shipping.