During the Macedonian Struggle (1904-1908), the marshy lake of Giannitsa was one of the main fields of fierce Greek-Bulgarian conflicts in Macedonia, which was part of the Ottoman Empire.

In the classic historical novel "In the Secrets of the Swamp" (1937), the iconic children's literature author Penelope Delta captures the dramatic events of the era, excellently combining the power of authentic historical material with the intensity of fiction. The narrative revolves around the actions of two children, Apostolis and Giovan, who assist the Greek guerrilla forces in their operations against the Bulgarian forces, while also following the struggle of Tellos Agras (Sarandos Agapinos) and Captain Nikiforos (Ioannis Demestichas), prominent historical figures of this period.

The archetypal landscape of the swamp, acts of heroism, the sense of patriotism, moments of humanity, as well as betrayals, individual dramas, and the inevitable harshness of war, constitute a fascinating read that, eight decades after its initial publication—and despite today's historical perceptions of the events it describes—retains its magic intact and is read with the same, undiminished interest.