According to the Treaty of Tilsit, Prussia had to support Napoleon's invasion of Russia.

Entity and relation annotations:
id: 0
type: entity
value: text: the Treaty of Tilsit
labels: <Regulation>
id: 1
type: entity
value: text: Prussia
labels: <Location>
id: 2
type: entity
value: text: Napoleon
labels: <Person>
id: 3
type: entity
value: text: Russia
labels: <Location>