Answer:
Believe this is WWII strategy of the allies. Early in the war Russia was bearing the brunt of German military might. He begged, chastized England and USA for not opening a western front (land invasion in France to "sandwich" the Whermact /German army to defend two fronts.
Step-by-step explanation:
England, America and other allies were tieing up German and Italian Axis forces in North Africa, then Sicily, on to Italy. That was not enough, seaboard invasion on D-Day June 6,1944 finally brought the second front that sandwiched Germany between Russia/USSR on the East and Anglo-American on the Western front
May God Bless all who gave so much to defeat Nazi tyranny. Civilians in Europe, Russia, Poland etc. suffered mightily.