I personally like to start a sentence with.. In order to quell/quench Baghdad uprisings, they unleashed poison gas on Baghdad's people. (if you are talking about the 1991 Baghdad uprisings) But you can also start with To if you like. I dont think carpet drop poison gas is an appropriate term; I have only heard of carpet bombing . The Baghdad uprising? was there a particular uprising, if so , yes, you can use the Baghdad uprising.

You must say "the Baghdad uprising". You cannot say "[no article] whole of Baghdad". Alternatively, you can say: "To quench Baghdad uprisings..." "... gas on all of Baghdad." Poison shouldn't be capitalized.