Specifically the declaration of martial law in Poland on December 13, 1981, to suppress the "Solidarity" union movement.
"Proljeće je čak i u decembru / trinaestog ili bilo kog drugog / proljeće stoji iza barikade s podignutom rukom" . azra_proljece_13_u_decembru_cover_by_pps
While your specific video by may sometimes be unavailable due to copyright issues, you can find other versions for reference: Original Version: Available on Spotify and Shazam . Specifically the declaration of martial law in Poland
There are various community covers on YouTube that can provide different stylistic ideas for your own rendition. azra_proljece_13_u_decembru_cover_by_pps