Bartels was transferred to 11./JG 1 on 27 January 1942, on the Eastern Front, where he would be awarded the Knight's Cross of the Iron Cross for 46 aerial victories.

On 10 March 1942, 11./JG 1 was redesignated 8./JG 5. Bartels was to become one of the most successful pilots of 8./JG 5. This unit was under the command of Hauptmann Hermann Segatz (40 victories, DK-G) and was based on the Northern or Polar front (ARTIK).

During this period, overclaims were made by both sides. JG 5 claimed some 72 victories in August 1942, but Soviet records indicate 24 Soviet aircraft lost with another 7 damaged and 13 aircraft missing, and another 4 were shot down by ground fire

Bartels recorded 47 Russian aircraft shot down in 100 missions in this Theatre, including 21 victories in September 1942 alone.

He makes an unconfirmed claim over a Russian Lagg on 5 November 1942

He received the Knight's Cross of the Iron Cross (Ritterkreuz des Eisernen Kreuzes) for scoring a total of 46 aerial victories on 13 November 1942.

Just before his unexpected transfer to Greece, Bartels scored 3 more victories on 23 March 1943.

In the Spring of 1943, Bartels was hastily transferred to JG 27 based in the Balkan Front/Mediterranean Theatre (AFRIKA), at the Greek airfield of Kalamaki...

From August 1943 he served with 15 Staffel of Jagdgeschwader 27 (15/JG 27). He had 49 victories to his credit at this time.

His Bf 109F “Black 13” was named Marga in honour of his Wife....

He scored another five victories, including a further three P-38s, shot down on 25 October (57-61).

On 17 November 1943, Bartels claimed another triple kill, 3x aircraft destroyed once again.

This time, it was 2x B-25's and a P-38 Lightning, ALL WITHIN 8 MINUTES!!!

By the end of the year 1943, his tally would reach 73 confirmed victories, 24 of these victories in 6 weeks; among them four each on 25 October 1943 and 15 November 1943.

He was then sent to Reichsverteidigung duties and operated in these duties during April and May 1944.

On 24 April 1944, Bartles gets into a fast moving dogfight with a handful of P-51D Mustangs of the 355th/357th and promply and supposedly quite easily shoots down 2 of them.

Four days later on 28 April, Heinrich once again gets into a serious dogfight over Laibach and quickly destroys 2x Mustangs of the 352nd FG, one of them Lieutenant Colonel Clark.

He claimed 12 victories, including three victories in a day on two occasions, before deploying to the Invasion front and fought in the Normandy Campaign from June to August 1944.

But Bartels never received the Oak Leaves in the end

By 23 December 1944, Bartels’ victory count had increased to 98, and at this time he was serving with 15./JG 27.

On 23 December, while supporting German forces in the Battle of the Bulge, he took off at 11:00 am with his flight. His wingman was Oberfähnrich Rolf Brand. Gaining altitude they flew to the Köln – Bonn area.

Over Bonn, at 7500 metres, they saw fuel tanks dropping in front of their noses. Those drop tanks came from P-47 fighters of the USAAF 56th Fighter Group "Red Noses" in pursuit of the aircraft flown by Heinz Rossinger.

Bartels promptly shot down one of the American P-47 Thunderbolt fighters on the tail of Rossingers' Bf 109.. Heinrich Bartels was never seen or heard from again.

It was his 99th and last victory.

This was also the very same day that 56th FG claimed 34 enemy aircraft destroyed and Dave Shilling shot down 5 aircraft in the same meele. No one saw Bartels get hit, crash or die. Heinrich Bartels failed to return and was declared missing.

24 years later, on 26 January 1968, Bartels’ Bf 109 G-10 (W.Nr. 130 359) “Yellow 13” was found at Villip near Bad Godesberg. In its cockpit was Bartels' remains and the remains of his uniform jacket with his Iron Cross 1st Class still attached, his wedding band with his wifes name inscribed inside, and his intact parachute, which is currently on display at the Deutsches Technikmuseum Berlin.

The following passage from Werner Girbig's "Six Months To Oblivion" gives a brief and chilling account of his loss: "Only a few hundred yards away, near the moated castle of Gudenau, a Messerschmitt struck with an incredibly violent impact and buried itself deep in the frozen ground. No parachute was seen, and it was to be 24 years, almost to the day (26 January 1968- LMR), before more was known about this crash.

It was the Bf 109G-10 of Oberfeldwebel Heinrich Bartels, who had destroyed a Thunderbolt just before he was himself shot down. This was the 99th kill scored by this 26-year-old holder of the Knight's Cross from Linz on the Danube, who had been flying with IV./JG27 since May 1943." (Girbig, p. 72)

From Ring and Girbig pp.302-303 ‘Flying with Bartels is halfway life-insurance’ the airmen say. A cloud of invulnerability surrounds him. He is a moral support to the young pilots. That is why it strikes the Geschwader especially painfully when at noon on the 23 December, it is established: Oberfeldwebel Heinz Bartels has not returned from a mission against the enemy!

Heinz Roesinger describes his last mission once again: “On this day I was a Rottenfuehrer in Heinz’s Schwarm. If I remember correctly, Oberfaehnrich Brand was his Kaczmarek. The scramble was at 11 O’clock. Because my machine would not start, I jumped into a machine that was standing on the edge of dispersal, which did not have a working high-altitude supercharger as it later turned out. I flew after the Staffel as it was forming up and still managed to reach my Schwarm. We were constantly climbing in the direction of Cologne-Bonn. Over Bonn at 7500m, the drop-tanks from Thunderbolts tumbled down in front of us. The “Red-snouts” were above us. During the constantly-climbing dogfight which resulted, I lagged more and more behind my Schwarm. Four Thunderbolts promptly banked in behind me. I was still able to see how Hein did a sharp left bank back to me and shot down a Thunderbolt. But then I became so busy myself that I completely lost sight of him and the others. During the wild dogfight, my ‘mill’ was shot in flames and I baled out over Meckenheim.”

Heinrich Bartels flew about 500 combat missions and shot down 99 enemy aircraft: 49 on the Eastern front with JG 5 and 50 with JG 27 in the Mediterranean and in Defence of Germany. His score included nine P-47s, eleven P-51s and fourteen P-38s! Bartels is buried in the cemetery of Wachtberg, Villip. close by is the grave of Oberst Johannes “Macky” Steinhoff.

Uwe Benkel, noted historian and aircraft recovery expert, also did a second recovery excavation of Heinrich Bartels G-10. There was some yellow paint flecks perhaps indicating that was the "13", although no definitive or partial figures were found. However, there were no indication or proof that the aircraft had rudder markings or his wife's name (Marga) like his earlier G-6. A wedding band was discovered with the wedding date and "Marga" inside the ring. That makes it pretty sure it was his aircraft, but markings are purely speculative including the style and placement of the gelbe 13.