A single Ukrainian tank brigade stood between the eastern suburbs of Kyiv and the Russian tank army.
The Ukrainian army's 1st tank brigade was outnumbered by 10 or so battalion groups from the Russian 41st Combined Arms Army, as well as adjacent Russian formations.
The 1st Tank brigade halted the larger Russian force in the first few days of the war in Ukraine, and then transitioned to an active defense and protected the city of Chernihiv for the next five weeks.
The 1st tank brigade and other reserve and territorial units were held out by the Russians. The Ukrainians regained control of the first of several main roads connecting Kyiv and Chernihiv on Thursday after a month of siege by the Russians.
The 1st Tank brigade is one of the best in the country. There are three tank battalions with the latest locally-produced T-64BM tanks and a mechanized infantry battalion. Each battalion has around 400 troops and 40 or 50 vehicles.
The brigade's support troops include three battalions, one each with 2S1 and 2S3 self-propelled howitzers and BM-21 rocket-launchers.
Heavy rockets and howitzers, as well as longer-range air-defense systems, are provided by other units.
The 1st Tank brigade fell into disarray after the collapse of the Soviet army. The Ukrainian army reconstituted the brigade in September of 2014, seven months after Russia invaded the peninsula and threw its support behind the rebels.
The 1st Tank brigade tried to break through the defenders of the airport. Two dozen tanks were lost by the Ukrainians.
The 1st tank brigade fought along trenches in eastern Ukraine after the airport debacle. The brigade was in Donbas in April of last year. The 1st tank brigade moved back to its garrison inside the nature reserve after the Russians began massing troops along the border.
The brigade was not in the area when Russia invaded. Like most Ukrainian units, it dispersed, rendering Russia's initial bombardment useless.
The 1st tank brigade concentrated its forces in time to intercept the 41st CAA, which was about to enter the city of Chernihiv. The U.K. defense ministry concluded that it was unlikely that Russia had achieved its objectives on the first day of combat.
The Ukrainian brigade fought hard, slowing but not stopping the encirclement of Chernihiv and at least one road to Kyiv. After two weeks of fighting, the Russians were on the verge of cutting off the defenders of Chernihiv.
The 1st Tank brigade and its associated reservists and territorials were alone. They defeated every Russian attempt to capture the city over the next three weeks.
The 41st CAA was in the area. Senior Russian officers were desperate to get the army moving. Ukrainian sources said Gen. Vitaliy Gerasimov, a deputy commander of the 41st CAA, died on March 7. The deputy commander of the 41st CAA was shot and killed a few days ago.
The Russians bombarded the city. At least one Russian warplane was shot down by air-defenders with the 1st Tank brigade. The other crew member died. The other was captured by the Ukrainians.
The 1st Tank brigade appears to have kept many of its T-64s through the siege warfare. The brigade uses the latest T-64BM with its uprated engine and armor. Analysts have confirmed the destruction of just two T-64BMs, both of which belonged to the Ukrainian army.
That doesn't mean the 1st Tank brigade hasn't lost tanks. The brigade hasn't lost many tanks, that photographic evidence is easy to find.
After suffering thousands of troops killed, wounded or captured, and also writing off thousands of vehicles, the Russians signaled a retreat from northern Ukraine starting the last week of March.
Analysts expect the survivors of the 41st CAA to regroup for a possible deployment to the wartorn areas of Donbas and Kharkiv. The Ukrainians liberated towns and reopened roads.
The next step for the 1st Tank brigade is not known. In order to relieve Kharkiv and to reinforce the front line through Donbas, Kyiv will shift forces east.
The role of the 1st Tank brigade in the next phase of the war will depend on how long the brigade needs to rest exhausted battalions, repair battered tanks and intake replacement troops and vehicles.