http://revach.net/article.php?id=3391

Section: Parshas HaShavua   Category: Life Lessons
Parshas Bishalach: Chasam Sofer - Armed But Not Dangerous
Krias Yam Suf is widely considered the greatest Nes of all time.  Why did it need to happen at all, asks the Chasam Sofer?  The pasuk clearly says that Bnei Yisroel left Mitzrayim, "Chamushim" armed.  Why could they not have a war with Mitzrayim that Hashem would help them win like He did so many other times even in the midbar?

He answers that it would have been improper for the Bnei Yisroel to raise their weapons against their former hosts, in whose country they resided for so many years.  The Torah even tells us (Devarim 23:8) "Lo Sisa'ev Mitzri Ki Ger Hayisa B'Artzo", do not despise a Mitztri because you were an alien in his land.

Despite the terrible treatment and being forced into cruel slavery by our "hosts", Hashem preferred to perform an incredible Nes rather than taking care of business in a very understated and natural way.  This underscores the incredible obligation of Hakoras Hatov, deriving from even the slightest benefit, irrespective of the benefactor's evil intentions.  We prefer to minimize out obligation of Hakoras HaTov by convincing ourselves that a favor done to us was really only self serving.  Irrelevant screams the Torah again and again!  It is even worth a Krias Yam Suf.