A Welsh tank unit (note the Union Jack and the daffodil logo)
taking part in Able Archer 83
This came while President Ronald Reagan was placing Pershing II missiles in Western Europe; 8 months after he made a speech declaring the Soviet Union to be "an evil empire"; 67 days after the Soviets shot down Korean Air Lines Flight 007; 42 days after Soviet Lieutenant Colonel Stanislav Petrov figured out that the detection of 2 U.S. nuclear missiles heading for Russia were a false alarm, and refused to give the order to launch a retaliation, thus becoming known (years later, once the world found out) as "The Man Who Saved the World"; and would be followed, 13 days later, with ABC airing the TV-movie The Day After, which imagined a nuclear attack on the U.S.
Able Archer 83 included some steps forward that previous exercises had not. These, on top of everything else that had happened in 1983, led the Soviet government to consider that this was a setup for an actual war. So they placed their military units on the highest possible alert.
Able Archer 83 ended on November 11 -- appropriately enough, the anniversary of the Armistice that ended World War I -- and so the Warsaw Pact forces, seeing that nothing further had happened, were ordered to stand down. This may have been the closest the world came to nuclear war, except for the Cuban Missile Crisis of 1962 and Col. Petrov's moment.
The 1980s -- especially the Autumn of 1983 -- were not "a simpler time." Not even for those of us who were kids at the time.