One of my reference books for incidents like this is THE SECRET RAIDERS by David Woodward, published by W.W. Norton & Co., © 1955. The book briefly describes merchant raider activity in World War 1 and then focuses in detail on World War 2.

Another interesting book from the British point of view during World War 1 has to be MY MYSTERY SHIPS by Rear-Admiral Gordon Campbell, published by Doubleday, Doran & Co., © 19129, commander of several of the disguised but heavily armed cargo ships that lured German U-boats (sometimes even after being torpedoed) close enough to be destroyed.

Cheerily,
Charley Noble