He was born on July 7, 1851, in Chalkida (the island of Evia) and studied law and politics in Paris. Returning to Greece, he worked as a lawyer for a short time before going into politics. Kalogeropoulos was first elected to the Greek parliament in 1885 representing Chalkida and was a friend of Harilaos Tricoupis. After the latter’s death, he followed his successor, Georgios Theotokis.

He was re-elected to parliament and held the following portfolios: Minister for Justice (1903), Finance (1904 & 1909), Interior (1905) in the governments of Theotokis. On September 16, 1916, he was appointed Prime Minister by King Constantine and also held the Finance and War Ministries. After the Royalist electoral win in November 1920, he served as finance minister in the Dimitrios Rallis administration. On February 6, 1921, he became prime minister for the second time and also was foreign minister until his resignation some two months later. His last political appointment was that of a foreign minister in the short-lived Triantafyllakos government just after the Asia Minor catastrophe.

During World War I, Greece found itself in the midst of a political schism between King Constantine and Prime Minister Eleftherios Venizelos. Constantine appointed prime ministers who were loyal and faithful in maintaining their master’s foreign policy of benevolent neutrality. Zaimis submitted his resignation on September 11, 1916, citing declining health reasons. There was more to his resignation in that he was keen to discuss with the Anglo-French alliance Greece’s involvement in the war. Obviously, Constantine wasn’t happy about changing his foreign policy. Therefore, Kalogeropoulos was tapped on the shoulder on September 16 to become Premier. There were three Germanophiles in his cabinet, which displeased the allied ministers in Athens. The Anglo-French opposed his ministry from the outset and the Venizelist press waged a fierce campaign against Kalogeropoulos.

Meanwhile, the Bulgarians had occupied Eastern Macedonia and Kavalla. The Bulgarian commander met his Greek counterpart, Hatzopoulos and proposed that Bulgarian forces would occupy Kavalla and defend the town against an allied landing. Hatzopoulos was advised not to oppose the Bulgarian occupation; otherwise, the Greeks would face serious consequences. Athens informed Hatzopoulos not to oppose the Bulgarians. There were Greek troops who wanted to join the National Defence movement under Venizelos in Salonika and some of them managed to join this movement. However, Hatzopoulos’ actions resulted in the 4^th army corps (officers and soldiers) being transported to Goerlitz, Germany as prisoners of war until the conclusion of hostilities. Athens had been kept in the dark regarding Hatzopoulos’ action.

On September 14, the allies sent a note to Constantine pointing out that they were establishing the ways and means of controlling telegraphic and postal communications. At the same time, a blockade of Greece’s Aegean coastline was established. The Anglo-French pressed Constantine to join their side in the war. Kalogeropoulos’ assurances of benevolent neutrality were unacceptable to them.

The premier was prepared for Greek involvement in the war on the condition that the military balance in the Balkans favored the allies; alternatively, there would be no Greek mobilization.

Before Greece’s intervention, Athens would consider itself freed of all engagements. Greece expected equal treatment in the alliance, financial and material support, and territorial compensation in Northern Epirus, Thrace, and Asia Minor. Strangely, the Dodecanese and Cyprus weren’t included in the territorial demands. The French premier, Aristide Briand supported this idea, whereas the British thought that it would drag out the negotiations. In the end, Constantine continued with neutrality and Kalogeropoulos had failed to secure allied recognition of his government. He was premier for only four weeks.

Eventually, Constantine abdicated under allied pressure and Greece led by Venizelos entered the war on the side of the allies.

In April 1919, Kalogeropoulos and Stratos addressed an open letter to U.S. President, Woodrow Wilson endorsing Greek territorial claims at the Paris Peace Conference. It stated: “The Greek people as a whole, independently of any divergence of opinion exclusively related to internal politics, solely aim to promote national claims, and believe that the only right solution of the eastern problems concerning Hellenism lies in the re-establishment of a single national Greek-State-constituted from the lands of the present Kingdom of Northern Epirus, Thrace including Constantinople with the Gallipoli Peninsula, of the vilayets of Aidin and Broussa, the coast of Nicomedia and Dardanelles, the Dodecanese and Cyprus-assuring the Greeks of the Pont an independent political life.” Their letter largely supported Venizelos’s position in Paris.

After the November 1920 elections, he served in the Rallis government during the Asia Minor campaign. He resigned his post on January 25, 1921, and within a few days became premier for a second time. His term lasted about two months and was replaced by Dimitrios Gounaris.

Kalogeropoulos’s crowning achievement was representing Greece as premier at the February/March Conference in London regarding the revision of the Treaty of Sevres. The British premier, Lloyd George considered him a person of “moderate and conciliatory views” but obstinate and unyielding on Smyrna and Thrace. Kalogeropoulos told Lloyd George that Greece could defend its new territories and easily defeat the Kemalists. Furthermore, Greece could increase her troop numbers by an additional two divisions in Smyrna. Lloyd George pressed him to make concessions in Smyrna but Kalogeropoulos needed to consult Athens. Kalogeropoulos stated that the Greek administration in Smyrna had established law and order and security for its inhabitants. To ask the Greek army to withdraw wasn’t a brilliant idea because it would be difficult to re-introduce them at a later time. It should be noted that there was active Italian propaganda favoring the Turks against the Greeks.

Kalogeropoulos received a reply from Athens that the Greeks had the unshakeable determination to crush the Kemalists and were ready to implement its engagements under the Treaty of Sevres. There also the issue of the repatriation of refugees into Smyrna which would come under the protective umbrella of the Greek army. Lloyd George thought that the Royalists were more difficult to deal with than the Venizelists.

During the conference, a proposal for an international commission to investigate the populations of Smyrna and Thrace was discussed. The Turkish delegates favored such a commission whereas the Greeks rejected it. Greece would not consent to a revision of the Treaty of Sevres, something which had the full support of the Greek people and the Greek Parliament.

On April 7, 1921, Kalogeropoulos resigned as premier and after the Asia Minor catastrophe in September 1922 declined an offer to be Premier. However, he served as foreign minister for a week in the Triantafyllakos government. After the military revolution in September 1922, he spent the remaining years as a private citizen. Kalogeropoulos died in Athens on January 7, 1927.