It shall be lawful for any State that had troops engaged in the battle of the Moores Creek National Battlefield, to enter upon the same for the purpose of ascertaining and marking the lines of battle of its troops engaged therein: Provided, That before any such lines are permanently designated the position of the lines and the proposed methods of marking them by monuments, tablets, or otherwise, shall be submitted to and approved by the Secretary of the Interior; and all such lines, designs, and inscriptions for the same shall first receive the written approval of the Secretary of the Interior.