Identify Symbol on Shield to Win

I have been working on several projects over the past 3 months.  Today I'm giving a challenge for the identification of the main symbol on the metal shield.  Respond with the name and history of the image on the shield.  Correct answers will receive prizes.  The response deadline is 8 May 2012 MIDNIGHT. Email responses to carlsart2010@gmail.com.  Must be at least 21 to participate in contest.