In 756, Pope Stephen II allied with the Frankish King, Pippin the Short, to gain independence from the Byzantine Empire.

On 25 December 800, the pope crowned Charlemagne, King of the Franks as emperor of the Holy Roman Empire at St. Peter's Basilica in Rome to reunite various regions of the former Western Roman Empire under a common rule.

The Holy Roman Empire lasted until 1806. This was significant because:

• Set a precedent for papal involvement in imperial politics which strengthen the Roman Catholic Church's power
• Suppress any religious practises against the Roman Catholic Church
• Spread Roman Catholic Christianity across Europe