Preceding the offensive, the Red Army had built up large amounts of materiel and manpower in the three bridgeheads. The Red Army greatly outnumbered the opposing Wehrmacht in infantry, artillery, and armour. All this was known to German intelligence. General Reinhard Gehlen, head of "Fremde Heere Ost", passed his assessment to Heinz Guderian. Guderian in turn presented the intelligence results to Adolf Hitler, who refused to believe them, dismissing the apparent Soviet strength as "the greatest imposture since Genghis Khan". Guderian had proposed to evacuate the divisions of Army Group North trapped in the Courland Pocket to the Reich via the Baltic Sea to get the necessary manpower for the defence, but Hitler forbade it. In addition, Hitler commanded that one major operational reserve, the troops of Sepp Dietrich's 6th Panzer Army, be moved to Hungary to support Operation Frühlingserwachen.