In the Balkan Wars of 1912-1913, the Greek army crossed into Macedonia and took possession of 51% of the whole country including its largest city of Salonica.

The Greek army captures Salonica

The decree of Georgios I, the King of the Greeks, issued on October 31, 1912, acknowledges by the king himself that the "territories in Macedonia (are) occupied by the Greek army":

Georgios I - The King of the Greeks

Taking into account the developed need for the urgent and temporary organization of the administration of the territories in Macedonia, occupied by the Greek army. At the proposal of the Ministerial Council, we have decided and command the following. The Minister of Justice Mr. K. Raktivan, as representative of the Greek Government, is instructed to organize the affairs concerning the temporary administration of the occupied territories. The president of the Ministerial Council is to announce and carry out this decree.

Salonika, October 31, 1912

Georgios Ministerial Council President Elefterios Venizelos Members:L.K.Koromilas K.D.Raktivan Eman Repulis I.D.Cirimokos L.Mihalakopulos H.A.Stratos

It is clear that Macedonia was not "liberated" by the Greek army (as the modern Greeks claim) today but occupied by the same. One liberates ones own territory from foreign rule, and only foreign territories are occupied

Thus, as a Dane, he was certainly a conqueror. At least, that is how he perceived himself. The same does not apply to the Greek people who were never fond of Monarchy, but were forced to have it in order to be recognized by the Western powers.