How did Rome change from a republic to a vast powerful empire despite threats to its unity?

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.

Your question cannot be answered because you are asking about two different things. A republic is a type of government. An empire is any vast holding, in Rome's case, territories. The two are different and one can't morph into the other.