in 2012 defense spending was 18.7% of all federal spending.....if one man was 18.7% as tall as the next man you would call him a dwarf.......
http://www.heritage.org/research/reports/2012/10/federal-spending-by-the-numbers-2012
The bold is pretty silly. I mean, of course a part of the budget is smaller than the whole budget. The comparison isn't defense to the overall budget, but defense to other specific spending categories. On the discreationary side of the ledger, defense is larger than everything else combined (4.3% of GDP for defense and 4.0% for everything else).