This infographic found on visual.ly is a great infographic about major wars of since America became a country. It goes through every war, from the American Revolution to post 9/11 and shows the amount of time spent in battle, the amount of money spent on war, and the number of lives lost.
According to this infographic, America has spent half of
it's its existence in war. Based on my knowledge of history, this is not terribly uncommon. Most countries have been in war in defense or offense over borders, money, or even love. Challenge your students to research some of the minor wars and find out the reasons behind them.
This infographic is also a great example of how to create an infographic. It uses a gun as a timeline, and a bulls eye to show lives loss. It is a great example of how to use implements from the subject to who information in an infographic.