The American people in their righteous might will win through to absolute victory This text implies that Roosevelt believed he had successfully

The American people in their righteous might will win through to absolute victory

This text implies that

 Roosevelt believed he had successfully argued the case to go to war

 Roosevelt believed those who had been unjustly attacked would triumph

 Roosevelt had cause to doubt Americans' willingness to enter into war

 Roosevelt had to convince Americans of the likelihood that a war could be won