Although the 7TP is often claimed to be the world's first (production) diesel-powered tank, this distinction actually goes to Japanese Type 89B I-Go Otsu, produced with a diesel engine from 1934 onwards.

[1] Barring that, the claim of a first purpose-designed diesel-powered tank is tied with Type 95 Ha-Go, whose series production also commenced in 1935.

After initial tests, it became clear that the twin-turret variant was obsolete and lacked firepower, so it was abandoned in favour of the more modern single turret design.

Although the tank fared well during field trials, the Romanian officers were not impressed by the armour of the Polish prototype and instead recommended the acquisition of the Czechoslovak LT vz.

It entered combat on September 4, 1939, and fought with distinction in a variety of roles, mostly as a mobile reserve and for covering the withdrawal.

Part of the battalion was destroyed in the Battle of Głowaczów, while the remainder on September 13 managed to break through to the other side of the Vistula, where it joined the Lublin Army and Col. Stefan Rowecki's Warsaw Armoured Motorised Brigade.

After the Battle of Tomaszów Lubelski, on September 21, 1939, the remaining tanks were destroyed by their crews and the unit surrendered to the Germans.

The battalion was then rallied and withdrew to Warsaw and then to Brześć, where it shielded the mobilization of the Polish 60th Infantry Division.

On September 15 it took part in a two-days long Battle of Włodawa, but suffered heavy losses due to air bombardment and was withdrawn southwards.

On September 15 the company was ordered to form a spearhead of the Polish attack aimed at linking up with the forces of the Poznań Army withdrawing after the Battle of Bzura through the Kampinos forest north of Warsaw.

The attack ended up as a minor success, although the German aerial bombardment caused heavy losses both in personnel and in tanks.

37 anti-tank gun used in the 7TP was able to penetrate the armour of any of the German tanks of the time, including the newest, the Panzer IV.