intervened
v.v. to get involved in a difficult situation to change what is happening or to help solve a problem.
v. to come between people, groups, or events to modify a process or prevent a specific outcome. Often implies an intentional interruption of a sequence of events.
The teacher intervened before the two students started fighting.
The central bank intervened in the currency markets to prevent the local currency from losing too much value.
Historians debate whether the empire would have collapsed as quickly had foreign powers not intervened in the internal succession crisis during the late fourteenth century.
The verb is intransitive and frequently takes the preposition 'in'.
The police intervened the protest.The police intervened in the protest.Intervene is intransitive; you must intervene 'in' a situation rather than intervening the situation directly.