I remember seeing a documentary stating something about cavalry charging tanks, and winning, because the tanks were "surprised" and distracted enough for polish tanks to dispatch enough panzers to make them withdraw. THe battle of Mokra I believe. I am not really sure it is true.
The documentary was pretty much correct, but it should underline that there was no mounted
As I wrote cavalry didn't charge at Mokra on horseback, but few counterattacks of Polish armoured vehicles, providing support for cavalry (which counterattacked dismounted, like infantry do), really took place:
"(...) Around 9:00, as the response to the first German assault, a counterattack of the brigade started. Crews of tankettes of the second platoon demonstrated unusual bravery, counterattacking (towards the Mokra II village) enemy tanks without Anti-Tank ammunition! One delayed TKS withdrew in parallel with attacking (in the second assault at 10:00) armoured vehicles of the enemy and - as Rajmund Szubanski writes - was destroyed by friendly fire of the HMG squadron of the 12th uhlan regiment. Plut. Marcin Wieliczko, deputy of the platoon's commander, was killed then, while his driver managed to jump out of the burning tankette.
After the next German assault (at 13:00), when tanks of the Pz.Rgt.35 from 4. Pz.Div. reached the large forest clearing near the village Mokra II, mjr. S. Glinski proposed to organize a counterattack of armoured vehicles of the 21st armoured unit. However, commander of the 21st uhlan regiment, ppłk. dypl. Kazimierz Suski de Rostowo, recognized this undertaking as unrealizable. Enemy armoured vehicles were superior to Polish in respect of armour and armament, which was proved by the slightly earlier attempt of reconnoitring the region of village Mokra I by armoured cars from the squadron of kpt. J. Zymierski. Platoon of armoured cars wz. 34-II was then forced to retreat and one car was destroyed. Commander of the vehicle, plut. Edward Dziuba, was seriously wounded.
After two hours of combats, when an assault of over 50 German tanks broke through the first defensive line and threatened the artillery positions (2nd battalion of horse artillery), the squadron of armoured cars and second platoon of TKS tankettes supported the counterattack of 2nd horse rifle regiment. Intervention of Polish armoured fighting vehicles caused considerable confusion disorientating the crews of German AFVs, who in the chaos of combats started to fire at each other - and the assault was repulsed. During the battle of Mokra on that day 3 armoured cars wz. 34 were lost and one damaged could be evacuated (and - most probably - repaired). This combat was resolved - not for the first time on that day - by cooperation with armoured train No 53 "Smialy", also attached to Wolynska BK. By evening the enemy pressure ceased completely. Germans bypassed positions of the brigade from the south."
This enemy which bypassed positions of the brigade from the south was 1. Panzer-Division.
On the next day - 2 September - AFVs of the 21st armoured unit (21 dpanc.) counterattacked twice:
For the first time in the morning, supporting the counterattack of 11th rifle battalion between the forest Lobodno and village Ostrowy - the counterattack succeeded and the situation was again brought under control (the German advance was halted). For the second time after 16:00, supporting the counterattack of 21st uhlan regiment which aimed at liberating the cut-off by German forces (Schtz.Rgt.12 and two medium tank companies from Pz.Rgt.35) in the forest Lobodno 2nd horse rifle regiment. This counterattack was caried out by the squadron of tankettes under command of por. L. Kozioradzki. It (together with uhlans of the 21st regiment) engaged German infantry and Panzers in combats and enabled the 2nd horse rifle regiment to escape the trap. Enemy of the brigade was 4. Panzer-Division.
On 2 September 21 dpanc. lost 4 tankettes and 1 motorcycle due to fire of German motorized artillery (that was supporting operations of Panzers and infantry) as well as 1 KIA (st. strz. Jan Krasinski) and several wounded.
Source: "12 Batalion Pancerny" by Jan Tarczyński (chapter about the 21 dywizjon pancerny, pp. 25 - 26).
Organization of Polish armored units (dywizjony pancerne) - Niehorster calls them "battalions":
http://niehorster.orbat.com/029_poland/ ... k_cav.html
Each of them had 13 tankettes (TKS or TK-3) and 8 armoured cars (wz. 34-II, wz. 34 or wz. 29).