awaken a sleeping giant

To rouse, provoke, or galvanize the enormous or unstoppable latent power of some person, group, or thing. The political candidate has captured the attention and enthusiasm of young people from many different demographics, awakening a sleeping giant among voters. The country may be neutral, but they have an immense standing army. I fear we may awaken a sleeping giant if we initiate an attack against them. If the prime minister keeps acting in this erratic and dangerous manner, I'm afraid he will awaken a sleeping giant and unify all those countries against us.