British Admiralty's Search for the Seeadler
Do you know where I might find information on the extent of Englands efforts to capture the Seeadler?
No I am not able to suggest where you may find that information.
I can't say I am aware of any concentrated efforts by the Royal Navy to hunt down Seeadler, she was only loose for 224 days, but she sailed about 30,000 miles in that time.
In April of 1917 she made it round Cape Horn in a storm, and sighted a British Armed Merchant Cruiser probably HMS Ortranto, but the Brits did not see her.
The previous month, Seeadler had caused some mayhem north and east of Rio de Janeiro, and British warships on the South Atlantic station no doubt were on the lookout for her.
After the Count had rounded the Horn, to throw any ships seeking him off the scent, he let go three captured life boats, ensuring they carried material identifying his ship, hoping to give the impression that Seeadler had sunk. A later report by the British indicated that this ploy was probably successful.
Unlike some of the other German Armed Raiders such as Moewe, who was avidly sought after , I think the Royal Navy did not make too many efforts to find and sink the wily Count and his sailing ship with an auxiliary motor. He was a nuisance but did not sink the total tonnage as did some of his fellow Raiders.
Sorry that I cannot be any more specific.