A distinguished staff officer and an ardent Venizelist and anti-royalist, Pangalos played a leading role in the September 1922 revolt that deposed King Constantine I and in the establishment of the Second Hellenic Republic.

In June 1925 Pangalos staged a bloodless coup d'état, and his assumption of power was recognized by the National Assembly which named him prime minister.

[2] His mother was descendant of the local Arvanite fighter of the Greek Revolution, Giannakis Meletis (Hatzimeletis), while his paternal side came from an aristocratic family of Kea island.

He did not have a chance to lead it to battle though, because when King Constantine abdicated and Venizelos took over the governance of all of Greece in June 1917, he was appointed chief of the personnel department in the Ministry of Military Affairs.

In late 1918 he was appointed chief of staff of the General Headquarters, holding the post until the electoral victory of the pro-royalist and anti-Venizelist United Opposition in November 1920, when he was dismissed from the army.

[2] On 14/27 November he was named Minister for Military Affairs and tasked with reorganizing the Greek army in Macedonia and Thrace, as the war with Turkey was not over, and an attack in the region was feared to be imminent.

[2] A staunch nationalist, Pangalos objected to the terms of the treaty, and declared that his troops would attack Turkey nonetheless in order to block the deal.

On 29 August 1926, a counter-coup led by General Georgios Kondylis deposed him, and Kountouriotis returned as president, while Pangalos was imprisoned for two years in the Izzeddin Fortress.

[1] He also played an important role, albeit from behind the stage, in the establishment of the Security Battalions, which he hoped to use against both the Communist-dominated National Liberation Front and against a possible return of King George II and the royal government from exile.

[5] Blume intrigued in the summer of 1944 to have Pangalos appointed prime minister of the puppet Hellenic State to replace Ioannis Rallis, who was very close to a nervous breakdown by that point.