I think they're exceptional FTSE 100 bargains to consider today. A FTSE 100 defence bargainKey numbers: price-to-earnings (P/E) of 17.1; price-to-earnings growth (PEG) of 0.3. Why buy Babcock shares? To put that into context, a £10,000 lump sum investment in this FTSE stock in in August 2021 would have turned into £44,260 today. Why on earth, then, might you want to consider the FTSE 100 company for your portfolio?