What really caused the 2nd explosion of the lusitania?

They concluded the second blast was a boiler explostion, which did not itself cause significant damage. I hope this helps!

determination

roosevelt believed that in light of the country's recent military successes, it was unnecessary to use force to achieve foreign policy goals, so long as the military could threaten force. this belief, and his strategy of “speaking softly and carrying a big stick,” shaped much of roosevelt's foreign policy.