Franklin Delano Roosevelt (FDR) was in office came into the presidency in 1933, when the United States (and much of the world) was mired in the Great Depression. The "unprecedented task" was to find a way out of that horrible time of economic collapse. The task he proposed, requiring "undelayed action," was the implementation of his New Deal programs to spur economic recovery. I won't go into what all the elements of the New Deal were -- you can look that up quite easily on your own!
Roosevelt was referring to the
significance of the Battle of San Juan
as it brought an end to the Spanish American War. Lt. Col. Theodore Roosevelt
led his “Rough Riders” up the San Juan Heights against heavy artillery fire to
help end the Spanish-American War.