Why did the Bf 110 struggle against the P.Z.L. P.11?

The Messerschmitt Bf 110's main weakness was its lack of manoeuvrability, a flaw that, as noted, could be mitigated with better tactics. Opposite it, Polish fighters offered better manoeuvrability than their German counterparts and, as a bonus derived from their configuration, a much better view from the cockpit. That relative scarcity of armament and engine power which made the P.11c seem vulnerable was precisely what made it more manoeuvrable and able to stand up to the Germans. The Polish monoplane could also dive at up to 600 km/h without risk of the wings coming off.

In every other respect the comparison was reversed: the P.11c was no match for the superior speed and firepower of the Luftwaffe fleet, particularly the Messerschmitt Bf 109 and Bf 110. With those advantages, the Bf 110 served with considerable success in the opening campaigns in Poland, Norway and France.

According to Luftwaffe records, the Germans lost 285 aircraft, with at least 110 victories credited to the P.11 against about 100 of its own aircraft lost. The efforts of the P.11c pilots during that month-long war nonetheless ended in futility.