The first and the third sentences contain parallel structures. Parallel structure, or parallelism, is the repetition of the same grammatical structure or form within a sentence, so it becomes more balanced, and, therefore, more readable and clear to understand.
In the first sentence, the parallel structure has been used in the comparison: "... would make war <em>rather than let</em> the nation survive and accept war<em> rather than let</em> it perish..."
In the third sentence the same grammatical form has been used too: "<em>all dreaded it </em>(1) <em>all sought to</em> avert <em>it </em>(2)."