What was president Franklin d Roosevelt greatest contribution while the nation recovered from an economic disater and faced another potential war in europe

President Franklin D. Roosevelt's greatest contribution was the reformation of financial regulations.

Explanation:

Franklin D. Roosevelt was the 32nd President of the United States and the only one elected four times into that position. He was first elected in November 1932. He was in charge of the US throughout the second world war.

According to White House archives, FD Roosevelt brought "recovery to business and agriculture, relief to the unemployed and to those in danger of losing farms and homes."

He also reformed Social Security, imposed heavier taxes on the wealthy, introduced new controls over banks and public utilities, and introduced an enormous work relief program for the unemployed.