Greenmantle

Greenmantle, published in 1916 by John Buchan, is the second novel in the Richard Hannay series. Set during World War I, it follows Hannay as he investigates rumors of a Muslim uprising and embarks on a dangerous journey through enemy territory to Constantinople. There, he and his allies work to thwart German plans to exploit religious tensions for their war efforts, culminating in the battle of Erzurum. This novel is notable for its exploration of themes related to war and espionage.