Do Now 11/15

Read this sentence from Paragraph 6.

Desperate for a Union general who would stand and fight, President Lincoln hired and fired many candidates with shocking swiftness in the first years of the war.

Now read this excerpt from a letter written by President Lincoln to a general in 1862.

I state my general idea of this war to be that we have the greater numbers, and the enemy has the greater facility of concentrating forces . . . we must fail, unless we can find some way of making our advantage an overmatch for his; and that this can only be done by menacing him with superior forces at different points. . . .

Taken together, the sentence and the excerpt from the letter suggest that President Lincoln was motivated by which belief?