Rome had a lot of emperors. Many died of different causes. Zero died of natural causes, and 13 of assassination or possible assassination. Soldiers in Rome wore breastplates and helmets when they fought. The soldiers fought the goths without any armour. Because they were to lazy and thought it was too heavy to carry. The failure to enforce I think weakened Rome. I think it failed to conscript more soldiers to the army.
Invaders from the Roman empire came from Asia. The Ostrogoths, Visigoths,