What is the subject of the sentence?

The story of the four hundred members of the 29th Cavalry and their heroic exploits on several battlefields (is, are) truly remarkable.]]> Is the subject of the sentence singular or plural?

The story of the four hundred members of the 29th Cavalry and their heroic exploits on several battlefields (is, are) truly remarkable.]]> The story of the four hundred members of the 29th Cavalry and their heroic exploits on several battlefields is truly remarkable. Type the correct form of the words in parentheses into the box, then submit it and say the sentence.

The story of the four hundred members of the 29th Cavalry and their heroic exploits on several battlefields (is, are) truly remarkable.]]>