In the winter of 1915, during the Serbian Army's retreat across Albania to the Greek island of Corfu, he evacuated General Petar Bojović from Scutari by plane, delivered mail by air and transported the Serbian Government's gold and hard currency reserves from Niš to keep them from falling into enemy hands.

Following the occupation of Serbia by the Central Powers, Tomić went to France and flew over the Western Front, where he had one confirmed kill.

He returned to the Balkans in late 1916, conducted combat missions over Bulgarian-occupied Macedonia and shot down one enemy plane.

Tomić continued flying after the war and became head of the Royal Yugoslav Air Force's pursuit squadron in Novi Sad.

In 1912, prior to the First Balkan War, it sent six soldiers to France to receive pilots' training and ordered 11 French planes.

[2] On 29 March 1913, Sergeant Tomić and Lieutenant Živojin Stanković spent 45 minutes flying over Scutari at a height of 2,200 metres (7,200 ft) and spying on Ottoman positions.

[5] In July 1913, Tomić flew several flights over Bulgaria, conducting reconnaissance missions and dropping small bombs.

Misha Glenny, a journalist who has written extensively on the Balkans, likens it to "a box kite on perambulator wheels".

On the afternoon of 12 August 1914, he flew a reconnaissance mission over Šabac, and disclosed to the Serbian High Command that, contrary to initial reports, the Austro-Hungarians had not set up pontoon bridges on the Sava and were attempting to cross the river with boats.

[6] The Serbians equipped their planes with 8-millimetre (0.31 in) Schwarzlose MG M.07/12 machine guns, six 100-round boxes of ammunition and several bombs.

On 22 October, he became the first Serbian pilot to face enemy anti-aircraft fire when his Blériot XI was targeted by Austro-Hungarian field batteries.

Tomić went on to participate in multiple combat missions, dropping explosive ordnance on Austro-Hungarian military positions and supply lines.

[9] In total, Tomić and Mihailović flew nineteen combat missions over the Banat between early May and late August 1915.

[11] The small Serbian Air Force withdrew from its headquarters in Banjica to Kruševac via Mladenovac, Smederevska Palanka and Jagodina.

In Kruševac, Tomić and lieutenant Živojin Stanković were tasked with destroying four obsolete planes to keep them from falling into enemy hands.

[12] Tomić continued south, successfully transporting the Serbian Government's gold reserves out of Niš and ensuring they did not fall into the hands of the Central Powers.

At about 10 a.m. on 17 April 1917, Tomić and his escadrille attacked a group of 14 Bulgarian planes conducting a bombing raid against the Serbian rear.

His plane sustained serious damage during the encounter; it was struck by a number of incendiary bullets and its fuel line was severed.

Following the Allied breakthrough in Macedonia, Tomić and his escadrille landed at Novi Sad, after which he was promoted to the rank of captain.