[5] During the second half of the 1800s, several military conflicts changed the balance of power in Europe and set off an arms race leading up to World War I.

[6] In addition to Krupp, one of the most profitable companies during this period was the Grüsonwerke of Magdeburg Germany that specialized in casting large components like armored gun turrets.

[7] However, their plan was dependent on the Belgians allowing Germany to cross their territory unopposed and Great Britain not honoring its treaty obligations to defend Belgium's neutrality.

Brialmont chose 15–21 cm (5.9–8.3 in) guns to arm his forts because he believed that if they could withstand enemy artillery of that size they would be effective.

Brialmont assumed that larger siege artillery would be too heavy to transport and too expensive for an attacker to have in sufficient numbers.

It also failed to take into account that Germany had heavy mortars like the 25 cm schwerer Minenwerfer that were light, mobile and numerous.

Since aircraft of the period were not yet capable of carrying large-diameter bombs the burden of delivering heavy firepower fell on the artillery.

The combatants scrambled to find anything that could fire a heavy shell and that meant emptying the fortresses and scouring the depots for guns held in reserve.

The gun barrels were placed on a simple box trail carriage made from riveted steel plates and there were two large spoked cast iron wheels at the front.

Its nearest German equivalent would be the 21 cm Mörser 99 which fired a projectile of roughly the same weight to a similar range but the M1891 was twice as heavy.

[14][15][16] Before entering World War I thirteen M1891 guns were removed from Romanian fortifications and placed on locally built garrison mounts to serve as heavy field artillery.