I was planning on just uploading the one song for each nation, as there's dozens for each, but you know what?
I reckon that the Poles deserve at least two, due how often people forget about just how massive a contribution they made to the Allied war effort.

Czerwone maki na Monte Cassino (The Red Poppies on Monte Cassino) is one of the best-known Polish military songs of World War II. It was composed in May 1944 in Italy, during the Battle of Monte Cassino, on the eve of the Polish Army's capture of the German stronghold. The song pays tribute to all of the Polish lives that were lost in the conquest of this monastery-turned-fortress by the Germans and their Italian Fascist allies.

Below is the recollection of Feliks Konarski, the lyricist for this song, upon performing it to the soldiers for the first time.

"For the first time singing Red poppies on Monte Cassino, we all cried. Soldiers cried with us. Red poppies, which bloomed over night, became one more symbol of bravery and sacrifice – a tribute of alive ones, whom for love of freedom died for freedom of people."

Lyrics: Feliks Konarski

Composer: Alfred Schütz

Soldiers of Second Polish Corps captured Monte Cassino on 18th May 1944. This song was written after the battle and it is a tribute to thousands of soldiers …