Parashat Devarim is the first Parsha in the Book of Devorim the 5th and final Chumash of the he Torah.
Moshe spoke word of rebuke to the entire Jewish Nation on that side of the Jordan in the desert, in the plain opposite the Red Sea, between Paran and Tofel and Lavan and Hazerot and Di Zahav. He did not openly rebuke them, out of respect for the Nation, but did so by alluding to the various incidents where they angered Hashem by mentioning the names of the places where they took place.
This rebuke was given in front of the entire Jewish Nation, so no one absent could later claim that had they been their they could have responded with defensive answers. Moshe therefore told them, since they were all there, anyone who had an answer, let him answer. 
Location Based Rebuke
- Desert - Moshe had mentioned the desert although they had already left it and were now in Arvos Moav, alluding to how they had angered Hashem in the desert during the 'Incident of the Complainers' where they had demanded meat saying it was preferable to have died in the Hands of Hashem in Egypt where they had meat.
- Plains - Moshe mentioned the Plains rebuking them for the sins of their worship of Baal Peor at Shittim which took place in the Arvos Plains of Moav.
- Opposite Red Sea - Moshe rebuked them regarding their rebellion at the Red Sea. Where petrified of the chasing Egyptians they had exclaimed why had Hashem taken them out of Egypt, was there a lack of graves there? Likewise they had been rebellious as they exited their crossing of the sea saying just as they had exited from one side, likewise the Egyptians would exit from another side, until Hashem had the sea spit out the bodies of the Egyptians proving they had died.
- ^ a b c d e f g h i Rashi Berashis 1:1
- ^ Shemos 16:3
- ^ Bamidbor 25:1
- ^ Shemos 14:11
- ^ Talmud Eruchen 15A