Final answer:
Constantine had to overcome rival claimants to the throne, economic instability, and religious conflicts before becoming sole emperor.
Step-by-step explanation:
Obstacles faced by Constantine before becoming sole emperor:
- Rival claimants to the throne: Constantine had to contend with other individuals vying for the title of Emperor, such as Maxentius, whom he ultimately defeated in the Battle of the Milvian Bridge.
- Economic instability: The Roman Empire faced economic challenges, including inflation and debasement of the currency, which Constantine had to address and stabilize.
- Religious conflicts: Constantine's adoption and promotion of Christianity led to conflicts with traditional Roman polytheism and other religious factions within the empire.