Who was the first person to shoot down an airplane using a ground-to-air cannon in a war?

Radoje Ljutovac (4 September 1887 – 25 November 1968), was a Serbian soldier from the village of Poljna, Serbia. Private Radoje Ljutovac fought in the First World War in the Serbian Army, and is officially credited with the first shooting down of a military aircraft with Ground-to-Air artillery fire.

He joined the First World War as a gunner in the Serbian Army and participated in their battles in 1914. During 1915, Serbia was again attacked by the Austro-Hungarian and the German Empire. Ljutovac was placed in the battalion artillery regiment "Tanasko Rajic", a special unit at the time, operating the newly formed anti-air battery.

On September 30, 1915, before noon, the alarm was sounded and his regiment went into battle stations; three planes approached Kragujevac and dropped their payload of 45 bombs, 16 of which fell on the Military Technical Institute, 9 on the train station, and the rest throughout the town. Ljutovac took aim with his cannon and fired at the planes eventually shooting down one of them.

After congratulating him on the venture, the commander gave him a horse, which he rode into town to find the burning aircraft. Together, with the plane, were the burned bodies of the enemy pilots. Ljutovac stood at attention and saluted. The pilots of the downed aircraft were Captain Von Scheffe and his rear/forward gunner Oton Kris. Ljutovac was then decorated with the Order of Karađorđe Star with Swords and was promoted to the rank of corporal.