In the early days of the war, on 12 August 1914, Maier and his pilot were brought down behind Russian lines by a malfunctioning engine while on a reconnaissance mission.

While serving with it, he received both Bronze and Silver Military Merit Medals, as well as the Order of the Iron Crown, Third Class with War Decorations and Swords.

[4] In April 1917, Maier requested transfer to a fighter unit and was obliged with command of Fliegerkompanie 55J (Flik 55J) in northern Italy.

Its roster included Georg Kenzian, Franz Lahner, Alexander Kasza, József Kiss, and Julius Arigi.

[5] Established at Haidenschaft in August 1917 to operate in the Battles of the Isonzo, it shifted in late October to Peregrine Airfield in the Tyrol.

On 15 November 1917, the trio attacked a formation of four Italian Caproni bombers; three of these were shot down in flames and Maier was credited with two victories.

Two days later, Maier and his wingmen shot down two reconnaissance machines, an Italian Savoia-Pomilio and a SAML south of Asiago-Arsiero.

[3][6] Subsequently, Maier was promoted to Hauptmann (captain) and awarded the prestigious Knight's Cross of the Order of Leopold with War Decorations and Swords; he was one of only 25 Austro-Hungarian so honored.

[4][7] As the Austro-Hungarian Empire dissolved into smaller constituent states, Maier was faced with choosing a nationality.