Why was communication so successful in the Roman republic ?

Need on these last 2 questions on my social studies homework 5 and 6 then i’m done with the homework

How did the battle of okinawa affect president truman’s decision to use the atomic bomb against japan? it showed that japan was close to surrendering. it showed that the us could not win the war without it. it showed that japan was willing to fight to the end. it showed the us could easily defeat japan.

What did the u.s. want to build on the land acquired through the gadsden purchase?