Joshua was born as Hosea ben Nun in Egypt, in the year 2406 from creation (1355 BCE); like Moses, he was hidden in the Nile after birth to escape Pharaoh's decree that all newborn Hebrew males be drowned in the river. For forty years, he was Moses' faithful disciple, "who did not budge from [his master's] tent" (Exodus 33:11; Joshua thus represents the trait of devotion and commitment — one of the five primary prerequisites to the acquisition of the wisdom of Torah).

In 1312, he was one of the twelve spies dispatched by Moses to scout the Land of Canaan in preparation for its conquest by the Children of Israel; it was then that Moses added the letter yud to Hosea's name, changing it to "Joshua" ("G‑d will save") as a prayer and empowerment that "G‑d shall save you from the plot of he Spies." Joshua was one of the two spies who brought a positive and encouraging report of the Promised Land, and tried to counteract the efforts of the other ten spies to dissuade the people from entering the land.

Upon Moses' passing in 1273, Joshua succeeded his master as the leader of the people of Israel. Under his leadership, they crossed the Jordan River on Nissan 10 of that year. For seven years, Joshua led the people in battle, defeating 31 kings and conquering their cities and territories, which comprised the bulk of the land west of the Jordan (Moses had conquered the lands on its eastern bank before his passing). For seven years after that, Joshua oversaw the process of dividing the land amongst the 12 tribes of Israel and allocating a portion to each family. He passed away on the 26th of Nissan, 2516 (1245 BCE), at the age of 110 years.

In addition to his roles as leader and warrior, Joshua was the second link in the chain of the transmission of Torah, receiving it from Moses and passing it on to the "Judges" who succeeded him.

Links:
The Vacuum of Choice
Moses' last day
Five Steps to Sinai