Engström, when he came on board with Tegelmund, found himself suddenly confronted by the Commander, with a stalwart bluejacket standing on either side of him. He was curtly informed that he could not go below.
“But you promised!” he shrieked, livid with vexation.
“True!” said the Commander. “But you call yourself Oscar Engström, of Malmö, and I happen to have the real Mr Engström here.”
The engineer went white to the very lips as Mr Engström, who had come post-haste from Stockholm in response to my urgent cable, emerged from behind the conning-tower, closely followed by myself. The false Engström began a vehement protest, but ceased suddenly, for, glancing round, he saw Tegelmund also under guard. The game was up!
A few minutes later, with Engström and Tegelmund safely in irons, the Admiralty experts who had come over from London began a minute examination of the wonderful “invention.” They soon discovered that the cases contained a jumble of wires and odds and ends of mechanical scraps simply thrown together to look complicated, and of no value whatever for the renewal of vitiated air.
The real object was only revealed when we had got to the very heart of the amazing collection of rubbish. There, cunningly hidden among much that was superfluous, was a highly efficient electric motor, wonderfully made and controlling a powerful bomb by machinery, set to detonate the explosive after six hours’ running. The machinery was to have been operated by the electric batteries of the submarine, and had the E77 gone to sea and begun the “tests” of the bogus apparatus, not a vestige of the vessel or the crew would have been seen again, and the secret of her loss would have been locked for ever in the depths of the Atlantic.
But this, we found, was only a part of the plot—perhaps even the least important part. Tegelmund, finding himself trapped, turned craven and revealed the whole story. The real object of the spies was to get the fullest possible details of the internal arrangements of a British submarine of the latest type, and how well they had succeeded was shown when we cast our net a little wider.
Directly Engström and Tegelmund were in custody, an innocent-looking signal flag flew from the masthead of the submarine, and the officials of the Sûreté ashore made their pounce. Thornton and Halbmayr were seized at once at their hotel, and in their possession we found a wonderful series of drawings in which many of the secrets of the submarine were fully explained. A telegram to Paris brought about also the arrest of Madame Bohman, and a few days later the German agents were safely immured in the convict prison at Tours, where they were sent by the sentence of a court-martial summoned immediately to deal with their case. Their guilt in this particular case was too clear for any possibility of denial, but I am glad to say that their arrest opened up a way to us to deal the Hun Secret Service a blow from which it has never fully recovered. Enormous piles of documents were seized and carefully examined, with the result that numerous associates of Thornton in England found themselves in durance vile “for the duration,” and so many fingers of the Hidden Hand were lopped off that the hand itself was badly crippled for many months to come. How the fingers grew and were again cut off I hope to tell at some later date.