Yehoshua 5:4

4 And this is the reason why Yehoshua did the Bris Milah: Kol HaAm that came out of Mitzrayim, that were zekharim (males), even Kol Anshei HaMilchamah, died in the midbar baderech, after they came out of Mitzrayim.

Yehoshua 5:4 Meaning and Commentary

Joshua 5:4

And this [is] the cause why Joshua did circumcise
Or the reason of the command given him to circumcise the children of Israel at this time, namely, what follows:

all the people that came out of Egypt [that were] males, [even] all
the men of war;
meaning such that were twenty years old, and upwards:

died in the wilderness, by the way, after they came out of Egypt;
not directly, but in a course of forty years, as they journeyed through the wilderness; this is to be understood with an exception of Joshua, Caleb, Eleazar but then there was a large number who were under twenty years of age, that came out of Egypt, and were now living.

Yehoshua 5:4 In-Context

2 At that time Hashem said unto Yehoshua, Make thee knives of flint, and do a second time the Bris Milah to the Bnei Yisroel.

3 And Yehoshua made him flint knives, and did Bris Milah to the Bnei Yisroel at Givat HaAralot.

4 And this is the reason why Yehoshua did the Bris Milah: Kol HaAm that came out of Mitzrayim, that were zekharim (males), even Kol Anshei HaMilchamah, died in the midbar baderech, after they came out of Mitzrayim.

5 Now Kol HaAm that came out were Mulim (circumcised); but Kol HaAm that were born in the midbar baderech when they came forth out of Mitzrayim, them they had not given Bris Milah.

6 For the Bnei Yisroel walked arba’im shanah in the midbar, until Kol HaGoy that were Anshei HaMilchamah, which came out of Mitzrayim, were consumed, because they obeyed not the Kol Hashem (voice of Hashem); unto whom Hashem swore that He would not show them HaAretz, which Hashem swore unto their Avot that He would give us, Eretz zavat cholov u’devash.