Anarchist anthem from the Spanish Civil War, using a 19th century Polish tune. I found it hard to track down a score of it.

https://en.wikipedia.org/wiki/A_las_Barricadas

X:1
T:A las barricadas
T:Warszawianka
T:Whirlwinds of Danger
C:Jozef Plawinski
M:4/4
L:1/8
Q:1/4=112
K:DMin
A2 A>G F2  F>E |D2 D>^C D2 F2 |E2 A>A  AG FE |DE FG  A4    |
A2 A>A d2 (A>G)|F2 F>E  D2 F2 |E2 A>A (AG)FE |D2 F>E D2 C2 |
F2 F>F C2  F2  |G2 G>G  C2 G2 |G2 c>G  B2 A>G|A2 A>A A3  A |
A2 A>A d2  A>G |F2 F>E  D2 F>A|E2 AA  (AG)FE |D2 F>E D2 C2 |
F2 F>F C2  F>F |G2 G>G  C2 G>G|G2 c>G  B2 A>G|A2 A>A A4    |
A>AA>A d2  AG  |F>FF>E  D2 F>F|E2 A>A  AG FE |D2 F>E D2 z2|]

I first encountered it in a display at the Museum of the History of Catalonia in Barcelona, but forgot about it until yesterday, when I heard some anarchists singing it at the demo for Catalonia outside the Spanish Consulate in Edinburgh. There are several versions on YouTube.