The verb intervene means to intentionally become involved in a difficult situation in order to change it, improve it or prevent it from getting worse.
Synonyms are arbitrate, intercede, interfere, or meddle.
The word origins in 1580s. It comes from Latin intervene meaning “to come between, intervene, interrupt, stand in the way, oppose, hinder”. It is derived from inter meaning “between” plus venire meaning “to come”. The sense of “come between, fall or happen between” is from 1600.
A senator intervened personally to stop the ongoing construction at the farm.
The Chinese continued to intervene in the fight of two colonies.
It was their duty to intervene in our election to avoid anomaly.