The German Reich - and from 1943, the Greater German Reich - certainly launched counterattacks after 1942---notably at Kursk on the Eastern Front of the European War and in the Ardennes Forest (the "Battle of the Bulge") in the Western Theater---but in a strategic sense she was absolutely on the defensive from early 1943 onward. That's because the German Army had been irretrievably smashed in the Battle of Stalingrad in the winter of 1942 and '43.

In the Eastern Front clash of titans with the Union of Soviet Socialist Republics (U.S.S.R.), the Germans had been thrown back from the suburbs of Moscow - the capital of the U.S.S.R. - the previous winter by an unexpected wintertime offensive. Though their retreat nearly became a rout, the Germans managed to hang on, and the 1941 operation, Operation Barbarossa, ground to a halt. Once the weather improved in the spring of '42, the Germans renewed their strategic offensive, with the goal now becoming to bypass and isolate Moscow and, especially, Leningrad (today back to its original name of St. Petersburg) to the north, while conquering the oil fields in the Caucasus to the south. Guarding the gateway to this region on a bend of the Volga River was Stalingrad.

The battle raged for nearly six months. The Germans called it "rattenkrieg", or "the war of the rats". For weeks on end, it was little more than snipers picking each other off from their nests in piles of rubble. Finally, the Russian autumn and winter set in once more, and the Germans were caught by a massive Soviet counterattack led by Army General Georgy Zhukov, of the Workers' and Peasants' Red Army, the Deputy Commissar of Defense and First Deputy Commander-in-Chief of the Armed Forces of the U.S.S.R., that trapped them inside the city. Adolf Hitler, the Chancellor and Führer of the German Reich, forbade them to try and fight their way out of the encirclement, and the Luftwaffe was unable to adequately supply the soldiers. In the end, the entire German 6th Army was annihilated, and only five thousand of its soldiers survived to return to Germany after her surrender in May 1945.

In response to this, Hitler recalled Colonel General Heinz Guderian, the former commander of the 2nd Panzer Army, who had previously sacked for saying politically incorrect things to the Führer about the Barbarossa offensive, and appointed him to the newly created position of Inspector General of Armoured Troops and later the Upper Command of the Army's Acting Chief of the General Staff. Guderian carefully rebuilt the shattered Panzer arm and was not in favor of Operation Citadel, which resulted in the Battle of Kursk. Hitler disagreed and pushed the plan forward because he thought he needed a German victory to reassure his faltering allies and to keep the Soviets at bay while the Germans took their industry underground and tried to perfect war-winning "wunderwaffe" (wonder weapons).

Kursk was incredibly bloody and enormously destructive to both sides, and while some have argued that the Germans were winning, their victory, had it come, would surely have been a Pyrrhic one. Meanwhile, Hitler decided to pull some of his units from the battle and redeploy them to face the Allied landings in Sicily and Italy. The Soviets were left holding the battlefield, and were able to replace their losses relatively quickly (if certainly not easily). The Germans, other than the Ardennes operation of 1944, no longer had the manpower for another strategic offensive.

So: the Eastern Front meatgrinder, coupled with the round the clock strategic bombing campaign by the United Kingdom and the United States, added to the invasions of Sicily, Italy, and France, spelled the end for the German's cause of the war. Other than localized counterattacks, they were on the defensive throughout the entire rest of the war after Kursk, with the sole sort-of exception of the Ardennes.

By the way: some will note that German munitions and weapons production actually peaked in 1944, which was also when the Allied strategic bombing offensive was heading for its zenith, and that's true as far as it goes. But while Greater German Reich was able to move many of its factories deep underground, even there they were not invulnerable to attack (as British superweapon scientist Barnes Wallis proved with his Tallboy and Blockbuster bombs). And beyond this, most of the critical petroleum and chemical factories and refineries supplying the German war effort could not be protected in this way. The end result was thousands of planes, tanks, and vehicles sitting idle for lack of fuel, and of course the delay in production caused by the German relocation of their factories also greatly aided the Allied efforts. But even if the Germans had been able to couple petrol with their vehicles and weapons, they, along with the rest of the Axis, had already been bled white. Just over half of the entire prewar adult male population of the German Reich died in the war. There was no one left to fly the planes or fire the weapons. The German war effort was kaput.