In my soft sci fi/science fantasy world, humanity lives in a hollow planet. A long, long time ago, an alien species put them there and created a field that prevents anything from entering the planet's orbit. Life in this hollow planet is not too different from Earth. The inside of this hollow planet has its own atmosphere and biosphere. An artificial star provides heat and life. Until ~200 years back, humanity didn't know that they lived inside of a planet. Despite being a sophisticated society approximately 500 years ahead of ours technologically - for instance, they've developed artificial wombs, gyrojet guns as the predominant form of firearm, and advanced prosthetic limbs - they've never been able to put anything manmade into space, since, before it manages to stabilize its orbit, it ceases functioning and crashes into the surface.
With all this in mind, how would wars change without the ability to use GPS and other satellite-based technologies?.
Rockets are shot into the sky from the surface, not from inside the planet.
To the human eye, the field is invisible. They can see the stars and the sun, but not the field.
For the past 200 years, humanity has known that they are living inside of a planet, rather than its surface. Before that, they had no clue.