He is best known for his participation in the Macedonian Struggle under the nom de guerre of Kapetan Nikiforos (Καπετάν Νικηφόρος).

[2] He participated in the Macedonian Struggle in 1906–07 under the nom de guerre of Kapetan Nikiforos, leading an armed band in the Giannitsa Lake area.

[2] With the outbreak of the First Balkan War in October 1912, he was given command of a gunboat, with which he participated in the operations in the Ambracian Gulf, but in early November he was detached to the Aegean fleet as commander of a landing detachment, with which he fought in the battles for the capture of the islands of the eastern Aegean.

Following Venizelos' return to Athens and his assumption of the government in June, Demestichas was made captain of the destroyers Niki (1917–18) and Nea Genea (1918–19), with which he participated in the anti-U-boat operations in the eastern Mediterranean.

[2] In 1919–20, he took part in the naval operations of the Asia Minor Campaign as commander of the destroyer Leon , but was placed on suspended duty on 27 April 1921, after the electoral victory of the anti-Venizelos royalist parties.

[2] On 6 March 1933, he became a member of the emergency military government under Alexandros Othonaios, that assumed power to counter the abortive coup attempt led by Nikolaos Plastiras.

[2] Demestichas took part in Plastiras' second failed coup attempt in March 1935, and after its failure managed to escape to Napoli in Italy.

[2] He is also a major character in Penelope Delta's 1937 historical novel The Secrets of the Swamp (Τα μυστικά του βάλτου), dealing with the Macedonian Struggle in the Giannitsa area.