The conference set the date for d-day, or operation overlord.

It was during the Tehran Conference that Stalin, FDR, and Churchill set the date and started the initial planning for D-Day, which was the first full invasion of Nazi-dominated Europe.

maybe by travelers or gossip

to protect the united states' role as a world leader, president truman wanted to prevent the soviet union from spreading communism beyond its post-world war ii boundaries. he declared that the united states must assist any nations struggling to prevent a communist takeover.