I think I will recall those battles directed by curious facts I remember about them..
The Battle of Westerplatte in 1939 lasted for one week. Polish defenders were also outnumbered and constantly shelled by Germans from the air, land and sea. Yet, only 15 Polish soldiers were killed in action. The poet who suggested in his famous patriotic poem that : they went to Heaven in rows of four.
obviously got carried away with that vision or simply needed it for the rhyme.
Another curious fact - the main commander broke down after 1 day and wanted to surrender but lower -rank officers protested and took real command from him.
Two films were made - in 1960s and 2015.
Older one - documentary version with comments
Battle of Ossów in 1920 during the Polish Bolshevik War.
Curious fact: priest Skorupka (Little Shell) who joined the army as a volunteer chaplain was killed in it. The legends says he was leading the soldiers to attack, lifting a crucifix in his hand. But it is only a legend - in fact, he was shot while blessing a fatally wounded soldier.
See the legendary version of the event: starts at 20:42