The second aliyah begins the drama of the story of the spies. They enter the land, and Rashi says that Calev, one of the spies, goes alone to Chevron where the patriarchs are buried, to pray that his companions shouldn't persuade him to do wrong.
The spies cut a huge cluster of grapes and carry it on a pole (this is a symbol of the Israeli tourist organization). The spies come back after 40 days. Rashi says this trip should have taken 80 days, but because G-d was going to keep the Jews in the desert one year for every day they were away, G-d shortened their trip.
The spies come back to the Jews in the desert and report that it is indeed a land flowing with milk and honey, but that it is well fortified and impossible to conquer. Calev speaks up and points out that Moshe split the sea, and got the manna and the quail, and that at his word anything is possible. He finished by saying that there is nothing to worry about. The Jewish people conclude that they would rather go back to Egypt. They spend that night wailing. This wailing takes place the night of the 9th of Av, and G-d says that if the people choose to wail for no reason on the 9th of Av, then He will give them something to wail about. As a result, both the first and second Bais Hamikdash's were destroyed, and other afflictions for Jewish people took place on that date, including WW-II, which began on that day too.