ROLLING THUNDER ADDRESS Defense Secretary Robert M. Gates waves to the crowd gathered to mark Rolling Thunder at the National Mall in Washington, D.C., May 29, 2011, saying it will be his last Memorial Day address before he retires in June. Rolling Thunder is an annual event in which thousands of veterans ride motorcycles through the city to call attention to prisoners of war and those missing in action. SHARE: Download: Full Size (0.06 MB) Credit: VIRIN: 954032-A-JJV93-935.jpg Photo Gallery