Original sentence: " Guderian also stated, however, that the firepower and frontal armor were good.At the end of the war it was the third most produced  German armored fighting vehicle.By June 1944, Panthers were about half of the German tank strength both in the east and the west.Heinz Guderian later remarked about the early Panther's performance in the battle: "they burnt too easily, the fuel and oil systems were insufficiently protected, and the crews were lost due to lack of training
Edited sentence: Abteilung/Panzer Regiment 6 (assigned to Panzer Lehr Division) with a total of 156 Panthers.After the losses of the Battle of Kursk, the numbers of Panthers slowly built up, and the percentage operational also increased as its reliability was improved.At the end of the war the Panther was the third most produced  German armored fighting vehicle.From June through August 1944, an additional six Panther regiments were sent into France.On the Western Front, at the time of the invasion of Normandy, there were initially only two Panther-equipped Panzer regiments - SS-Panzer Regiment 12 and I.The highest total number of Panthers listed as operational was achieved in September 1944, when some 522 Panthers were listed as operational out of a total of 728 assigned to the Eastern Front.The maximum number of Panther tanks recorded as being assigned to the Western Front during the Normandy phase of the war was only 432.With the successful breakout of Allied forces following Operation Cobra, most of the Panther regiments were wiped out in the retreat through the Falaise Gap as the German forces were forced to abandon almost all of their armored vehicles