This is both true, and humorous. A lot of advances in mechanical computing were driven by the needs of WWI and WWII artillery battalion colonels, and ship captains - hitting distant, often-times moving targets at different elevations, and in various wind conditions.
For example, the Mark I mechanical computer[1] could, when pointed at a target, measure its distance, altitude and heading, its own ship's speed, pitch, and heading, current windspeed - and combine that with the chosen projectile type, weight, propellant type, and current temperature - all to compute a firing solution that had the best chance of sinking ships adorned with swastikas, or a rising sun.
Not a general-purpose computation machine, but work on these sorts of devices heavily overlapped with work on programmable computers.
That was my dad, in WWII. He was the only one in his unit who could do the math. He kept going AWOL but they couldn’t do more than bring him back down to private because no one else could do the trig.
Quite literally a killer app, at that. As were many of the other earliest uses of computers -- wartime cryptanalysis and numerical computations for nuclear weapon development.
For example, the Mark I mechanical computer[1] could, when pointed at a target, measure its distance, altitude and heading, its own ship's speed, pitch, and heading, current windspeed - and combine that with the chosen projectile type, weight, propellant type, and current temperature - all to compute a firing solution that had the best chance of sinking ships adorned with swastikas, or a rising sun.
Not a general-purpose computation machine, but work on these sorts of devices heavily overlapped with work on programmable computers.
[1] https://en.wikipedia.org/wiki/Mark_I_Fire_Control_Computer