Masquerading as the SS Aud —an existing Norwegian vessel of similar appearance— the Libau (also known as SS Castro) set sail from the Baltic port of Lübeck on 9 April 1916, under the Command of Karl Spindler, bound for the south-west coast of Ireland. Under Spindler was a crew of 22 men, all of whom were volunteers. The Libau/Aud, laden with an estimated 20,000 rifles, 1,000,000 rounds of ammunition, 10 machine guns, and explosives (under a camouflage of a timber cargo), evaded patrols of both the British 10th Cruiser Squadron and local Auxiliary patrols.

After surviving violent storms off Rockall, the Libau arrived in Tralee Bay on 20 April. There they were due to meet with Roger Casement, Lieutenant Monteith and the Irish sergeant, Casement boarded first the U-20, but it had to turn back with rudder problems and instead was taken on the U-19, commanded by Raimund Weisbach, who had previously served as torpedo officer on U-20 and had launched the torpedo that sank Lusitania. During his brief command of U-19, Weisbach delivered Roger Casement along with Bailey and Monteith to Ballyheige Bay, Co Kerry. Due to a combination of factors (primarily as the ship carried no radio and was unaware that the date for its arrival off Fenit had been altered from Thursday, 20 April to Sunday, 23 April) the transfer of arms did not take place. The Libau, attempting to escape the area, was trapped by a blockade of British ships. Captain Spindler allowed himself to be escorted towards Cork Harbour, in the company of Acacia class sloop HMS Bluebell. The German crew then scuttled the ship.

Spindler and crew were interned for the duration of the war.

At this point Roger Casement and his companions who had been landed by the submarine U-19 in Kerry had been captured in McKenna’s Fort, between Ardfert and Tralee .

The car-load of Volunteers who were supposed to meet Spindler had crashed, many miles away, near Kenmare so there was no hope of an organised transfer of arms. With Spindler and his crew on a ship with no radio or other means of communicating their plight the poorly organised gun-running plan was nearing an end.

Photo: Roger Casement on the Aud with Robert Monteith in April 1916