Three years before World War II began in Europe, General Motors signed an agreement with Lilpop, Rau and Loewenstein Company in Warsaw to assemble Chevrolet cars and trucks, and Buick 90 limousines. This company had specialized in building railroad cars for many years, but after the invasion and occupation of Poland by the Nazis at the end of 1939, they ceased operations, as did many other factories and enterprises in Poland. In this state of war it was impossible to continue manufacturing, however, numerous vehicles had been built and imported in the previous years.

When the Warsaw Uprising started in early August 1944, the idea of creating an improvised armored vehicle came up immediately in an effort to offset the otherwise insurmountable odds that the partisans faced. Chevrolet trucks that had been assembled by Lilpop, Rau and Loewnstein were the first choice for such a tall order.

Historian Norman Davies, in his book God's Playground, writes, "The Resistance Movement flourished from the start. For the Poles, there was no question of collaboration. There was never a Polish Quisling … When it was seen that no advantages were gained by submission, increasing numbers turned to resistance."

A great example of the ingenuity and perseverance of the AK (Home Army) was the creation of improvised armored vehicles. One was called Kubus and still exists, on display in the Warsaw Military Museum. It was built in ten days at the Powisle Electrical Plant machine shop on a 157-in Chevrolet chassis of 1938 vintage. The work of mounting the armor plate was assigned to Edmund Frydrych who was an experienced craftsman at the plant. It was then turned over to Walerian Bielecki and another welder named Adolf Leszek, under foreman Jozef Fernik. Kubus was the nickname of Jozef Fernik's wife, who had been a doctor before she was killed by the Wehrmacht a few weeks earlier.

As construction began on Kubus, the wartime gasoline shortage was an immediate concern, so, like many vehicles during WW II on both sides in Europe, Kubus was modified to run on wood gas. In order to mount the armor plating, the partisans at the electrical plant used both acetylene and electric welders, and gathered sheet metal from wherever it could be found in the vicinity. Some of the best plates came from safes which had hardened steel. In order to determine which pieces were best suited for various parts of the vehicle, the workers tested the sheet metal by firing point blank with different rifles. As a result, they decided not to position any of the 6 mm (approx. 1/4-in) sheet metal perpendicular to the ground, as that position was most vulnerable to penetration.

Consequently, the entire armor plating was welded to the truck at the optimum angles. In addition, the thin metal plate was doubled in many areas and had a 3 cm (.72-in) gap between layers that was filled in with wood ash to prevent heavier gun fire or shrapnel from piercing the metal. There was no way to obtain heavier armor plate, and at least this kept the weight down since the Chevy had its capacity limitations. However, experiments showed that the ash did not help much, so this idea was abandoned in favor of enlarging the air gap from 3 cm to 6 cm.

The 1938 Chevrolet 157-in chassis was particularly well suited for the heavy armor plate body because the chassis was built using 7-in deep frame channels that were 7/32-in thick. Flanges were 2-3/8-in and there were six cross members, according to factory literature. With 6.50-20 6-ply front tires and dual 7.50-20 10-ply rear tires, the truck had what the factory specs called "Gross Allowable Weight" of 13,300lb. The chassis with cab weighed 3,5601b, leaving a considerable 9,740lb for armor, wood gas generator, armament, and crew. Front springs were 36-in long, semi-elliptic with nine leaves each. Rear springs were 45-in long with ten leaves each.

The six-cylinder overhead-valve engine had an SAE 29.4 hp rating, or 78 brake hp at 3200 rpm. The rated torque capacity was 170-ft-lb at 1550 rpm. The motor had four main bearings and used drop-forged crankshaft and connecting rods, heat-treated, and a drop-forged camshaft, case-hardened. The crankshaft alone weighed 68lb. Lubrication was accomplished through direct pressure using a gear pump and splash system. Carburetor was from Carter and electrical system from Delco-Remy. A governor for heavy duty use was optional, limiting the top speed to 45 mph.

Kubus was designed to carry up to twelve persons, and the first assignment was an attack at the nearby University of Warsaw. The enemy, who was holed up and shooting down from the buildings, had a bunker in front of the main gate preventing entry. Fortunately for the AK soldiers, the Wehrmacht did not have tanks or armor-piercing weapons in this area at that time.

The hatch at the top of the Kubus created an extremely vulnerable situation, making an easy target of anyone who entered or exited the vehicle. Consequently they decided to put a door underneath where the crew and transported soldiers could enter and exit, which was feasible due to the Chevy's relatively high ground clearance, even with flat tires. Nevertheless, this was a severe limitation, but there was no time to develop a heavy hinged door. Small openings on the sides of the cab were primarily gun slots but also helped visibility; however, night driving was extremely difficult since it had only a narrow slit for a windshield.

On August 23 Kubus was put into action, carrying eleven AK soldiers plus the driver, who were armed with a Russian machine gun, a flame thrower, and an assortment of rifles and handguns. Joining the attack against the German position at the University was a Sd. Kfz. 251 D armored transporter half-track, which had been captured on August 14 from the SS "Viking" Division. A number of men followed behind the vehicles on foot.

The first action was blowing up the huge steel front gates, which had to be done using an additional PIAT round and some ramming with the half-track. Most of the Germans in the front bunker were killed and others retreated. Gunfire erupted from the windows of the library, killing the AK unit's leader.

The arrival of two other groups of partisans from the other side was delayed. With heavy machine gunfire raining down from the building the resistance fighters decided to retreat, but the Kubus refused to start. The wounded were loaded up onto the half-track. After several frantic minutes, the Chevy engine, running on wood gas, finally came to life and the column evacuated from the area. Even though there were casualties and the coordination with the two other groups had failed, the attack was considered a success in that it boosted the morale of the soldiers while causing the Germans real concern. A second partially-armored vehicle, again using a 157-in Chevrolet cab-chassis but of earlier vintage, was captured from the German Post Office in Warsaw. It was used briefly before being destroyed during the incessant bombing of Warsaw.

Kubus was used two more times to storm the University side gates with a modicum of success. When the AK soldiers were forced to retreat from the area of Warsaw, Kubus had its ignition system removed to keep it from being used by the enemy. Amazingly, it survived the war and was restored by one of its original builders, Jozef Fernik.

For all the perseverance, bravery, and capture of enemy materiel, the Resistance was finally for naught, because section after section of Warsaw fell at the end of September 1944, and the AK was completely surrounded and over-powered. Without the expected outside support and intervention which had been previously ex-pressed or promised by British, American and Soviet forces, surrender was imminent.

During the Uprising of 1944 the AK lost 20,000 of its own members plus there was an additional loss of 225,000 Polish civilians, all of them women, children, and the elderly. The Jewish Ghetto had already been entirely cleared of human life during the Warsaw Ghetto Uprising of 1943.

After the Wehrmacht took the AK as prisoners of war, the remaining 550,000 civilians of Warsaw were evicted from the city, and Hitler ordered that Warsaw be "razed without a trace." Bombers continued to destroy buildings and demolition crews blew up remaining structures with dynamite and flame-throwers.