((a)) ** .—** The Secretary of the Army may make studies and investigations and, where necessary, surveys of all battlefields within the continental limits of the United States on which troops of the United States or of the original 13 colonies have been engaged against a common enemy, with a view to preparing a general plan and such detailed projects as may be required for properly commemorating such battlefields or other adjacent points of historic and military interest.

((b)) ** .—** The Secretary of the Army shall include annually in the Department of the Interior appropriation estimates a list of the battlefields for which surveys or other field investigations are planned for the fiscal year in question, with the estimated cost of making each survey or other field investigation.

((c)) ** .—** No real estate shall be purchased for national military park purposes by the Federal Government unless a report on the real estate has been made by the Secretary of the Army through the President to Congress under subsection (d).

((d)) ** .—** The Secretary of the Army, through the President, shall annually submit to Congress a detailed report of progress made under this subchapter, with recommendations for further operations.