Note: The Shabbos Torah Reading is divided into 7 sections. Each section is called an Aliya [literally: Go up] since for each Aliya, one person “goes up” to make a bracha [blessing] on the Torah Reading.
1st Aliya: The laws of the Red Heifer, are detailed. In Nissan of the 40th year, Miriam died. The well dried up and the nation gathered against Moshe and Aharon to complain about their thirst.
2nd Aliya: The hitting of the rock occurred and Moshe and Aharon were forbidden to enter into Eretz Yisroel. Edom refused to allow the Jews to travel through their land.
3rd Aliya: Aharon died and Elazar succeeded his father as Kohain Gadol. They encountered the southern Canaanites (13 miles west of the Dead Sea) and bested them in battle. Following Aharon's death the protective clouds departed and the nation began to complain about the living conditions. G-d sent poisonous snakes to attack the nation and Moshe was instructed to create the copper snake on a stick to miraculously save those having been bitten. The nation traveled to Yeshimon northeast of the Dead Sea.
4th Aliya: In the conclusion of Chukas, the nation was refused access to the lands of Sichon and Og and Moshe led them into victorious battle against them. Parshas Balak begins with King Balak's offer to Billam the Prophet to curse the Jewish people and G-d's refusal to allow him to accept.
5th Aliya: Balak sent a second negotiating team and Billam was given permission to go. Along the way the incident with the talking donkey occurred.
6th Aliya: Billam failed his first two attempts at cursing the Bnai Yisroel and blessed them instead.
7th Aliya: Billam attempted his final curse but again blessed the Jews. As he left in disgrace, Billam told the assembled coalition of kings of their eventual destruction by the Jews. As a parting shot against the Jews, he advised Balak to seduce the Jewish men with Midianite women which would bring G-d's wrath down upon the nation. The Parsha concludes with the incident of Baal-Peor and Pinchas's heroism.
In the year 2779 Yiftach HaGiladi became Judge - Shofet. Yiftach is described as a gifted warrior who was seemingly unworthy of becoming the Shofet. His brothers had cast out Yiftach because he was the son of a concubine. While away from his family Yiftach gathered around himself an army of outlaws. Due to the oppression and tyranny of Ammon, Yiftach was asked by the elders of Gilad to return to the family and lead them against the forces of Ammon. Yiftach was victorious and remained Shofet for six years.
There are a number of reason why the story of Yiftach was selected to complement Parshas Chukas. First of all the issue of leadership. The Talmud tell us that "Yiftach in his generation was like Samuel in his generation."
Although Yiftach was not the greatest scholar, he nevertheless was the recognized leader and a prophet. As such he was accorded the absolute support of the Halacha and the people. This support can at times appear as dogmatic as the law of the Red Heifer. However, our absolute support for our acknowledged Torah leadership is the foundation of our legal system and the transmission of Torah from generation to generation.
The second reason has to do with the battle with Sichon. Sichon was king of the Ammonites who had taken possession of lands once belonging to Moab. Sichon refused to allow the Bnai Yisroel to pass through his lands and went to war against them. Sichon was destroyed and his lands were forfeited to the Bnai Yisroel. In our Haftorah, the king of Ammon, as cousins to the Moabites, claimed legal ownership to the lands which Moshe had taken from Sichon, who had taken them from Moab.