Copy 162 of 300 ORO Log No. 56656 HOME DEFENSE DIVISION PASSIVE DEFENSE GROUP Report ORO-R-17, Appendix B Published December 1956 Effectiveness of Some Civil Defense Actions in Protecting Urban Populations (u) Appendix B of Defense of the US against Attack by Aircraft and Missiles (u) by we John Balloch Annex A by G. Trevor Williams Annex B by Oscar Sutermei ster Authorized by Cth, Gpetnse Director ORG OPERATIONS RESEARCH OFFICE The Johns Hopkins University Chevy Chase, Maryland SPECIAL HANDLING REQUIRED NOT RELEASABLE TO FOREIGN NATIONALS EXCEPT NONE