mdd
let me explain something to you
Israel has fought numerous wars over the course of it’s short history and most of it’s wins are miraculous, the chilonim didnt need the bachurim then and instead said it was b/c of kochi v’atzam yadi
the reason dovid, moshe and yehoshua needed an army is because you still need to do hishtadlus (its like saying why did they need to go to work in the times of dovid hamelech, it must mean Hashem doesnt provide for them)