Explain the importance of D-Day for the Allies.

D-Day, June 6, 1944, is the day that British, Canadian,
American and Free French Allied Forces invaded occupied France, and began the liberation
of Europe from Nazi Germany.

D-Day was not the turning
point in the war; the tide had clearly turned in the Allies' favor the previous year, as
the Soviet Red Army was progressively moving the Eastern Front westward. However, the
Soviets' progress was slow. D-Day helped to dramatically accelerate the German defeat by
opening up a front in the West, so that they could not devote all of their resources to
fighting the USSR. With the Allies now battling the Nazis on both sides, the war was
concluded in Europe within a year.

Some argue as well that
D-Day prevented a Soviet domination of all of Europe (instead of just the East), as
well. Had the Americans/British not put their armies on Western European soil, the
Soviets might well have been tempted to occupy the entire continent at the war's
end.

Answer

If they had spent
couple more years 'building up' their forces miles away from the main (Eastern) war
front, then the war would have ended with the victory of the Soviet Union and without
much Anglo-American involvement.

'D-Day' is more of a
political event - it actually prevented USSR from capturing territory east of the
Elbe.