Stan wojenny Anglais:

martial law was declared

impose/declare martial law

to proclaim/declare martial law

The country is under martial law.

The Soviet-run communist government declared martial law

On 13 December 1981 the communist authorities imposed martial law in Poland

ˌmartial ˈlaw noun [uncountable] a situation where the army of a country controls an area instead of the police during a time of trouble to declare/impose/lift martial law The city remains firmly under martial law. ▶ stan wojenny

In December 1981, the Communist government declared martial law in Poland. Martial law in Poland was lifted in 1983.