R&D soars during war, at least for war relevant technologies. Rockets, jet engines, aviation, synthetic fuel, chemistry, smokeless gunpowder, steam powered ships, nuclear fission... You name it. And that is in addition to all the stuff needed to actually build those things.
If you think industrial production isn't invested in during war you should fresh up on any modern war since WW1.
If you think industrial production isn't invested in during war you should fresh up on any modern war since WW1.