When Moshe began to speak the words of the reproof, the Midrash relates that the earth and heavens shook, the sun stopped shining, the wind died down, all animals were silent, and our forefathers cried out from their graves. They asked Hashem, "How can our children survive all these harsh punishments? Even our merit will not be able to stop this from happening." Hashem responded that His promise to keep Bnai Yisreal alive to build the Bait Hamikdash had not been nullified, and He would save Bnai Yisrael from complete destruction.
The curses, which came true in the times of the destruction of both temples, are as follows:
Failed buisness dealings: When the Jewish people stray from Hashem, He will first cause their buisness to fail. Produce will be hard to come by, children will leave their parents, and farm animals will die. During times of siege the Jews inside a sieged city did not have enough food, so their children and animals died.
Sickness: With a lack of food and water, epidemics will spread through the land killing much of the population.
Defeat at battle: Without supplies, their enemies will be free to attack and there will be no way to prevent them from entering the walls. This is how the two Batei Mikdash, as well as many other cities, were destroyed by the Babylonians and later the Romans.
Confusion: With disease ravaging the population and no cure to be found, the land will be thrown into chaos, and there will be no order in the cities.
Failure: Bnai Yisrael will not succeed in any of their endeavors. They will build houses but not be able to live in them. Their animals will stray and be taken from them. The fruit of their labor will be eaten by the enemy. Indeed, every time the enemies went through the cities, they stole all the Jews' produce, animals, and houses, leaving the Jews powerless.
Exile: The final curse given is that of exile. When the Jews do so much wrong, they no longer are worthy of even living in the land, so they must be removed from it. This, of course, is what happened after the destruction of the Batei Mikdash, when most of the Jews were exiled to the lands of their conquerors.
Each curse, however, has an opposite blessing that speaks of healing and success. If we follow the ways of Hashem and the teachings of Chazal, we will be able to make the Torah's blessings come true very soon, Am Yisrael's health will be restored, and the Bait Hamikdash will be rebuilt.