
herrschen
to rule
To exercise power over a country or a people, typically as a king, emperor, or dictator.
Der König herrschte über sein Reich mit Weisheit und Strenge.
The king ruled over his realm with wisdom and severity.
to rule / prevail
Loading your saved state.

to rule
To exercise power over a country or a people, typically as a king, emperor, or dictator.
Der König herrschte über sein Reich mit Weisheit und Strenge.
The king ruled over his realm with wisdom and severity.

to prevail
To be present, dominate, or prevail. Used for conditions, moods, opinions, or weather situations.
Nach der überraschenden Nachricht herrschte betretenes Schweigen im Raum.
After the surprising news, embarrassed silence prevailed in the room.

to have control over
To have control or mastery over something, for example over feelings, urges, or a complex situation.
Es ist eine Kunst, in stressigen Momenten über die eigenen Emotionen zu herrschen.
It is an art to have control over your own emotions in stressful moments.
The verb 'herrschen' (to rule/prevail) is related to the noun 'der Herr' (the lord, the master). It describes the action of acting like a Herr — that is, exercising power or being dominant.
Der Burgherr herrschte über die gesamte Region.
The lord of the castle ruled over the entire region.
The subject of the sentence reveals the meaning: if the subject is a person (king, dictator), it is about exercising power. If the subject is an abstract condition (silence, chaos, cold), it means 'to be present' or 'to prevail'.
Der Diktator herrschte mit eiserner Hand.
The dictator ruled with an iron fist.
When a person rules over a territory or people, the preposition 'über' with the accusative is always used.
Die Königin herrschte viele Jahre über ein großes Reich.
The queen ruled over a large empire for many years.
To describe a condition or atmosphere, 'herrschen' (to prevail) is very often used with the impersonal pronoun 'es' as the subject. The actual topic then follows in the sentence.
Auf der Party herrschte eine ausgelassene Stimmung.
There was a cheerful mood at the party.
to master / control / dominate
Both herrschen über and beherrschen can express having control over one's own feelings. Beherrschen is the usual and more direct form for this, while herrschen über sounds more marked and describes control as a kind of power. In normal conversation, beherrschen is usually the better choice; herrschen über is also possible, but less neutral.

Mit großer Disziplin herrschte er über seine Gefühle und blieb ruhig.
With great discipline, he kept his feelings under control and remained calm.
Mit großer Disziplin beherrschte er seine Gefühle und blieb ruhig.
With great discipline, he controlled his feelings and remained calm.