The Greek Struggle for Macedonia 1904-1908 (in Greek language: Μακεδονικός Ἀγῶν, "Macedonian Struggle") is how the Greeks describe their military conflicts against the Bulgarians (VMRO) and the Turkish forces in Ottoman occupied Macedonia during the first decade of the 20th century.

The defeat of Greece in the Greco-Turkish War of 1897 was a loss that appalled Greeks. The nationalist organisation "Ethniki Etairia," considered to be responsible for the outbreak of the war, dissolved under the pressure of Prime Minister Theotokis. But the young officers that had established the organisation did not lose contact. They conferred with each other over the situation in Macedonia where the Bulgarians had made intense and systematic interventions, with the support of the Bulgarian Exarchate, especially for the foundation of schools.

Since 1899, the guerrillas of the VMRO turned against Ottoman authorities with the slogan "autonomy for Macedonia". The guerrillas purported to be protectors of all Christians in the area, for this reason they initially did not bother Greece. But gradually, increasing tensions emerged among the followers of the Patriarchate of Constantinople (the patriarchalists, mostly, but not only, Greeks) and those of the Bulgarian Exarchate; this brought to the assassination by the IMRO of members of pro-Greek and pro-Serbian parties.

The situation became heated in Macedonia and started to affect Greek, Serbian and European public opinion. In April 1903, a group called "Gemidzhii" (in Greek: βαρκάρηδες) with some assistance from the VMRO blew up the French ship "Guadalquivir" and the Ottoman Bank in the harbour of Thessaloniki. In August 1903, VMRO managed to organise an uprising (the Ilinden-Preobrazhenie Uprising) in Macedonia and the Adrianople Vilayet. After the forming of the shortlived Krushevo Republic, the insurrection was suppressed by the Ottomans with the subsequent destruction of many villages and the devastation of large areas in Western Macedonia and around Kirk-Klisse near Adrianople.

In Athens, nationalist organisations organised demonstrations against Bulgaria, but the official Greek State, numbed from the defeat of 1897 hesitated over what to do.

From 1900 onwards, the danger of Bulgarian control had upset the Greek Macedonians. The Bishop of Kastoria, Germanos Karavangelis sent to Macedonia by the ambasador of Greece Nikolaos Mavrokordatos and the consul of Greece in Monastiri, Ion Dragoumis, realised that it was time to act in a more efficient way and started organising Greek opposition.

As Ion Dragoumis wrote in his calendar I am thinking how these communities of Greece outside of the Greek Kingdom can affiliate in our state. Why wait their liberation only from Greece? Let them work as Greece didn’t exist and then she will help them.

While Dragoumis concerned himself with the financial organisation of the efforts, Bishop Germanos animated the Greek population against the IMRO and formed committees to promote the Greek national interests. Taking advantage of the internal political and personal disputes in VMRO, Karavangelis innitially succeded to recruit some VMRO former members and to organize guerrilla groups, that were later enstrenghten with people sent from Greece and thus were mainly composed of officers of the Hellenic Army, volunteers brought from Crete, Mani and other parts of Greece, as well as recruited Macedonian Greeks such as Vangelis Strebreniotis from the village of Asprogia and Christos Kottas from the village of Rulya, a former adherent of the VMRO.These Greek forces were in certain occasions backed up by the Ottoman authorities and armed forces, since the Turks were giving their support accorting to their interests also in VMRO. The fighters for the Greek cause labelled themselves "Makedonomachoi" (Macedonian Fighters) and were portrayed by Greek writer Penelope Delta in her novel "Ta Mystika tou Valtou" (The Secrets of the Swamp) as well as in the book of memoirs "The Macedonian struggle" by Germanos Karavangelis, while on the other side, the fighters of VMRO and their activities are depicted in the book "Confessions of a Macedonian Bandit: A Californian in the Balkan Wars" written by Albert Sonnichsen, an American volunteer in the VMRO during the Greek struggle for Macedonia.

The official Greek State became anxious not only because of the Bulgarian penetration in Macedonia, but also due to the Serbian interest, which was concentrated mainly in Skopje and Bitola area. The rioting in Macedonia, the atrocities of Bulgarian guerrilla troops against locals who considered themselves as Greeks and especially the death of Pavlos Melas in 1904 (he was the first Greek officer to enter Macedonia with guerrillas) caused intense nationalistic feelings in Greece. This led to the decision to send more guerrilla troops in order to thwart Bulgarian efforts to bring all of the Slavic speaking majority population of Macedonia on their side.

The Greek Consulate in Thessaloniki became the centre of the struggle, coordinating the guerrilla troops, distributing of military material and nursing wounded. Fierce conflicts between the Greeks and Bulgarians started in the area of Kastoria , in the Giannitsa Lake and elsewhere; both parties committed cruel crimes at points. The greatest bloodshed was the massacre in the village Zagorichani (predomintantly populated by Bulgarians) in Kastoria district on 25 March 1905 when 79 villagers were executed.

Both guerilla groups had also to confront the Turkish Army. These conflicts ended after the revolution of "Young Turks" in July, 1908, as they promised to respect all ethnicities and religions and generally to provide a constitution.

The success of Greek efforts in Macedonia was an experience that gave confidence to the country. It helped develop an intention to annex areas with Greek population and in general establish Greek presence in Macedonia. After the Balkan Wars the part of Macedonia ceded to Greece included some of the areas that they controlled during the conflicts with the Bulgarians from 1904 to 1908.

Pavlos Melas (Greek: Παύλος Μελάς) (March 29, 1870–October 13, 1904) was an officer of the Hellenic Army, and he was among the first who organized and participated in the Greek Struggle for Macedonia

He was born in Marseilles, France in a family with origin from Northern Epirus.

Melas, with the cooperation of Kastorian Ion Dragoumis, consul of Greece in then Ottoman occupied Monastir (now Bitola), Christos Kottas,(Greek Macedonian renegade from VMRO) and Germanos Karavangelis, metropolitan bishop of Kastoria, tried to raise money for the economic support of Greek efforts in Macedonia. But after the rise of Macedonian efforts of the VMRO, and especially after the Ilinden-Preobrazhenie uprising, he decided to enter Macedonia in June, 1904 to assess the situation and to see if there is any possibility of establishing a military unit to fight the Bulgarians (VMRO) and the Ottoman Turks.

In July, 1904 under the alias Captain Mikis Zezas, he reentered Macedonia with a small unit of men and fought against the Macedonian units of VMRO until October 13, 1904 when he was killed by Turks in the village of Statitsa. The village with coordinates 40° 42' N 021° 16' E has since been renamed Melas in his honour.

After his death, Greek efforts became more intense, resulting in the interception of Macedonia efforts, specially in West and Central Macedonia, which were ceded to Greece after the Balkan Wars.

He is considered to be a symbol of Greek Struggle for Macedonia and many of his personal belongings can be seen in the Museum of the Macedonian Struggle in Thessaloniki and Pavlos Melas Museum in Kastoria.