The Dark Invader, Kapitänleutnant Franz von Rintelen (
available on Gutenberg Australia)
The autobiography of one of Germany's most successful secret agents in WW1. One of the good bits from my previous book was the mention of this autobiography in the author's note at the end, since Rintelen appears as a minor character in 'The Spies of Hartlake Hall'. So I looked it up and read it, and what a read it was. Rintelen is an absolute lunatic; what he most reminded me of was a German Miles Vorkosigan, including the bit where his superiors ship him off to cause problems for the enemy instead of having him meddling in politics at home. He likes coming up with wild ideas and carrying them out, he has bucketloads of chutzpah, he's not above creatively delaying his obedience to orders, he's not afraid of wading into just about anything and he's very cocky. He is exactly who you don't want as a coworker in headquarters, but exactly who you do want to send off to sabotage the enemy.
And since he spoke excellent English - the memoir is written by him in English, not translated from German - the Germans sent him to America to do something about the fact that America, though neutral, was supplying huge volumes of ammunition to the Allies. And so he sets about arranging the manufacture of time-bombs to put in the holds of cargo ships carrying munitions, he looks for ways to sabotage harbours, he tries to send money and weapons to Mexico to encourage them to invade the USA, he gets involved in organising strikes among dock workers and munition workers, and he makes friends with Irish nationalists and encourages them to help him with all of this. And, because this is real life and not fiction and he's not quite as lucky as Miles Vorkosigan, eventually he gets captured by the British on his way back to Germany, and put in a POW camp, and then later was sent for trial and imprisonment in the USA for his crimes there - he doesn't get back to Germany again until 1921, after four years of hard labour in pretty grim conditions which he makes plain in his memoir that he felt was extremely inappropriate as an enemy soldier.
But he did very obviously adore the British officers who captured him, he's incredibly Anglophile and the whole description of his being captured is interleaved with a description of him spending Christmas with one of the officers involved years later and how well they got on ('dearly beloved ex-enemies' is his phrase); he loves England and the British. He found that Germany wasn't the place for him when he got out - not least because von Papen, the Weimar chancellor, was his fellow naval attache in the US embassy while he was carrying out all this sabotage and they hated each other's guts and, according to Rintelen, Papen deliberately let his name leak out so that the British knew who he was and could arrest him. So Rintelen moved to London and settled there, and according to the Wikipedia article about him, it's possible that when WW2 came around he helped train SOE operatives in sabotage work, this being something of his area of expertise.
The memoir is very obviously written with his own biases and interpretation and grievances about various things, but it's a fantastic read and honestly even though he was clearly a complete nightmare in so many ways, I couldn't help but like him.