What factors led to the decline of the Roman republic and the rise of the Roman empire?

The Roman Republic began to decline when farmers began to lose sales due to grain coming in from conquered lands. When Rome conquered groups of people, they forced them into slavery, and often to work in wealthy land owner's latifundia. So when grain was pouring in from latifundia all over the republic at low costs, farmers in Rome were forced to sell their land and move to the city in search of work; Joining the crowds of already unemployed, lower class citizens, riots began breaking out. The new wealth in the city from the latifundia caused greed and corruption among the upper class. The Gracchus brothers attempted to reform Rome's republic, but the Senate was angered by their attempts to take power from them; the brothers were killed in waves of street violence. Unable to solve its problems, Rome plunged into a series of civil wars, with many armies fighting for one commander. These wars eventually resulted in Julius Caesar emerging victorious, and taking over the new Roman Empire.