Military background information:
Lothar Gruber with Army Group North and the invasion of the Soviet Union

First, the question arises: in which unit did Lothar Gruber (the author of the diaries and images) serve? The information in the diary is rather vague, as no division is mentioned, and some names in the image captions and the diary itself are misspelled or imprecise.

It is quite certain that he was deployed with Army Group North (in German).

The artillery mentioned in the diary belonged. to Artillery Regiment 193 (in German). Both the aforementioned French 15.5 cm battery and the details regarding the first snowfall of 1941 match.

The division in question is the 93rd Infantry Division (in German).

. Evidence for this includes its commander (from October 1, 1943), Lieutenant General Karl Löwrick—mentioned in the diary as a recipient of the Oak Leaves—and the entry "Reg. Cmdr. Colonel Löverik" (dated May 17, 1943). These individuals are likely one and the same, assuming Löwrick was promoted in the interim.
I received the following information regarding this (thanks to the contact in Vienna!), which I reproduce below:
"It is almost certainly the 93rd Infantry Division, which fought for a time as part of the XXVI Army Corps. Its commanders included Lieutenant General Otto Tiemann, while General Wodrig commanded the Army Corps."

The situation regarding the regiment is not entirely clear. It is likely the 272nd Grenadier Regiment sein (in German).In February 1945, the remnants of the 272nd Grenadier Regiment were transported from the pocket to Pillau. . See "Kurlandkessel" (in German).

It is clear regarding the battalion. There is a photograph with the caption: "Awarding of the Knight's Cross to Major Müller, Oct. '42" Walter Müller was the commander of the II Battalion, 272nd Grenadier Regiment, and received the Knight's Cross on October 21, 1942.

Regions and places in the Baltic states

Front line near Leningrad, 1941–1944

Places, lakes, and rivers mentioned

Koplino Kolpino
"Doppelname": (lit. double name) nickname for Troitza Schawitza
Owinovo or Awinovo
Oranienbaum
Dno
Pustinky
Petrowo
Krasnoje-Selo
Newa
Newa-Bogen (Front sector)
Szablino Sablino
Sankowa
Tigoda (River)
Peterhof (Country estate)
Gostilizy
Welikije-Suki Welikije Luki
Bol Kamenka
Loknya
Barki
Dunajewo
Wolchow (Fluß)
Ljuban
Tossna (town & river) Tosno (town) Tosna (river)
Iwanowskoje
Narva
Lawolosstje
Tigoda-Brücke
Wetno
Cholm Kholm
Porozk
Woronino
Novaija
Pleskau
Lkrekino (auch Lrekino)
Peipas-See
Krassni-Bor Krasnij Bor
Neva
Luga (Fluß)
Luban
Trachowschtschina-Sowat
Chablino (Choblino) Sablino

Thanks to [name] for correcting the place names. Serge!

The non-commissioned officer school in "Deba," Poland, mentioned in the field post and the 1943 war diary, refers to the military training ground—still used today by the Polish armed forces—located in present-day Nowa Dęba.
It remains unclear what the passage in the field post from Deba—dated August 26, 1943—refers to: "...for who knows what good it served. I am not yet allowed to write to you about what happened here, but I thank God that I was not there."

Btl. Gef. Std.: Battalion Command Post
Fldw.: Sergeant (Feldwebel)
Stuka: Dive-bomber
Art.: Artillery (jargon: *Ari*)
Gef St.: Command Post
Pak-Stand: Anti-tank gun position
Kp.: Company
MG-Stand: Machine-gun position
Rgt.: Regiment
Uffz.: Junior NCO (Unteroffizier)
HKL: Main battle line (combat front)
M. Gr. W.: Automatic mortar
Gr. Werfer: Mortar
V-Wagen: Supply truck

Military Operations in the Baltic States and Besieged Leningrad

Eine einleitende kurze Zusammenfassung der Operation "Barbarossa". Bei dieser Seite lohnen sich auch weitere Klicks!

Bei der Frage ob der Überfall auf die UdSSR ein Präventivkrieg war, haben die Gegner dieser These die Oberhand behalten, doch war bei dem Charakter der beiden Diktatoren ein Krieg früher oder später wohl unvermeidlich. Hitler sah einfach den Zeitpunkt als für ihn günstig an. Die von Stalin durch Mord ihrer Führungselite beraubte "Rote Armee" konzentrierte in geradezu dilletantischer Weise im grenznahen Raum ihre Kräfte, dies war jedoch keine Vorbereitung für einen Angriff. Das erklärte Ziel von Fall 21 "Barbarossa" war auf jeden Fall die Eroberung von "Lebensraum", die ansässige Bevölkerung sollte entweder verhungern oder nach Sibirien umgesiedelt werden.

Operative Planungen der Wehrmacht für den Krieg gegen die Sowjetunion

World War II operations. Eastern Front 1941-45. Battles of 1938-40. Sammlung von Lage- und Operationskarten der sowjetischen Seite. Leider sind die Pläne meist in kyrillischer Schrift.

Die Tragödie von Leningrad ein Aufsatz aus einer Wochenendbeilage der  "Westfälischen Rundschau". PDF-Download

Der Name Wolchow ist auch mit dem Namen Andrei Andrejewitsch Wlassow und dem tragischen Schicksal  der "Wlassov-Armee" verknüpft.

Der Russlandfeldzug 1941–1945 bei Wikipedia.

Das Unternehmen Barbarossa von Wigbert Benz zeigt, daß schon mit der Planung des Feldzuges der Hungertod von bis zu 30 Millionen Sowjetbürgern billigend in Kauf genommen wurde.

World War II casualties 🇬🇧. Estimates of the war's death toll vary widely. Figures from the former Soviet Union, in particular, are unreliable. German casualty figures for the final months of the war are also unreliable due to the collapse of administrative systems. Millions of people lost their lives even after the official end of the war—whether in Allied captivity, through expulsion from eastern Germany, or as a result of Stalin’s reprisals against former Soviet POWs and the mass deportation of entire ethnic groups suspected of collaborating with the Germans. This includes the Vlasov Army, whose members disappeared after being handed over to Stalin—in some cases through the use of force by the Western Allies.

I would like to thank Ms. Dörte von Westernhagen for the correction that, in the Wehrmacht, "V-Wagen" stood for "supply truck" (Versorgungs-LKW); she cited Hagen Fleischer, *Im Kreuzschatten der Mächte. Griechenland 1941–1944*, Vol. 2 (Frankfurt am Main, 1986), p. 82, as the source.

Thanks to Karl for correcting the tank types.

Thanks also to Martin for pointing out—regarding the same section—that Figure 67 shows the modified chassis of a tank.

I thank Vladislav for the information about Sablino and the link to the Yandex map.