Answer:
The correct way to write the sentence "the war was over soldiers spread baseball across the U.S" is the following:
The war was over, and soldiers spread baseball across the U.S
Explanation:
In order to connect the two independent clauses "the war was over" and "soldiers spread baseball across the U.S" you first need to use a conjunction, in this case the word "and". when you are using a conjunction to link two independenc causes, you need to add a comma before the conjunction, therefore the corrected sentence would be: The war was over, and soldiers spread baseball across the U.S.