The Junkers Ju.88 A-4, was the most
important version of all Ju.88 A-series and
it entered service in very small numbers in
1939, equipped significant numbers of units
during 1940, and was the most important
German bomber at the start of Operation
Barbarossa in 1941. The A-4 solved the
problems that had limited the performance
of the A-1, increasing the wingspan, using more powerful engines as
1,400hp Jumo 211F or 211J, fortifying the internal armor (especially
around the cockpit), and increasing its rate of fire, carrying five guns
and a bomb load of 7,936lbs.