It's well known that Mars has a very weak atmosphere as a result of billions of years of solar wind bombardment. Mars lacks a sufficiently large magnetic core to generate a magnetosphere strong enough to block the solar wind.
My civilization has found ways to generate enormous magnetic fields (without breaking the laws of physics) and they want Mars to have an Earth like atmosphere, eventually. They know they need to solve the magnetosphere problem first or any atmosphere they add will be wasted effort.
How much energy will it take to generate an Earth equivalent magnetosphere for Mars using technological means? Altering Mars' crust and core isn't an option for solving this problem.