And the people of Israel set out and camped in Oboth. And they set out from Oboth and camped at Iye-abarim, in the wilderness that is opposite Moab, toward the sunrise. From there they set out and camped in the Valley of Zered. From there they set out and camped on the other side of the Arnon, which is in the wilderness that extends from the border of the Amorites, for the Arnon is the border of Moab, between Moab and the Amorites. Therefore it is said in the Book of the Wars of the LORD,
“Waheb in Suphah, and the valleys of the Arnon, and the slope of the valleys that extends to the seat of Ar, and leans to the border of Moab.”
And from there they continued to Beer; that is the well of which the LORD said to Moses, “Gather the people together, so that I may give them water.” Then Israel sang this song:
“Spring up, O well!—Sing to it!— the well that the princes made, that the nobles of the people dug, with the scepter and with their staffs.”
And from the wilderness they went on to Mattanah, and from Mattanah to Nahaliel, and from Nahaliel to Bamoth, and from Bamoth to the valley lying in the region of Moab by the top of Pisgah that looks down on the desert. (Numbers 21:10-20 ESV)
Whereas Israel, 40 years earlier, had staged the invasion of Canaan at her southern border near Kadesh, now God moves her to the eastern border, across the Jordan River. Details of the journey and the wars are being kept by Jewish recorders/historians. They include songs that were sung in joy over such blessings as the provision of water from wells.
By staging them on the east, Israel will have to make a river crossing to enter Canaan, an opportunity for God to do a miracle. And they will have to fight armies outside of Canaan who feel threatened by them. There are Canaanites on the east side of the river, the Amorites, and God has determined to judge them through Israel.
How do you prepare for battle? What memories can you call upon, what songs can you sing, and what history gets you motivated and gives you strength? God has done amazing things in your life and the lives of others before you and intends for you to lean on the past in this way to give you power for the present as you recall His marvelous deeds done through your predecessors and in your own life.
In the Wikipedia article, Standing on the Shoulders of Giants:
The metaphor of dwarfs standing on the shoulders of giants (Latin: nanos gigantum humeris insidentes) expresses the meaning of “discovering truth by building on previous discoveries”. This concept has been traced to the 12th century, attributed to Bernard of Chartres. Its most familiar expression in English is by Isaac Newton in 1675: “If I have seen further it is by standing on ye sholders of Giants.”
The attribution to Bernard of Chartres is due to John of Salisbury. In 1159, John wrote in his Metalogicon: “Bernard of Chartres used to compare us to dwarfs perched on the shoulders of giants. He pointed out that we see more and farther than our predecessors, not because we have keener vision or greater height, but because we are lifted up and borne aloft on their gigantic stature.”
The visual image (from Bernard of Chartres) appears in the stained glass of the south transept of Chartres Cathedral. The tall windows under the Rose Window show the four major prophets of the Hebrew Bible (Isaiah, Jeremiah, Ezekiel, and Daniel) as gigantic figures, and the four New Testament evangelists (Matthew, Mark, Luke, and John) as ordinary-size people sitting on their shoulders. The evangelists, though smaller, “see more” than the huge prophets (since they saw the Messiah about whom the prophets spoke).