The Art of War: The album of the same title is strongly inspired by the work of Sun Tzu, and the titular song is all about it and includes an excerpt or two in the song.
Badass Army: The Carolean's Prayer paints the soldiers under Charles XII as this, which is Truth in Television. hell, the whole album has the Swedes being total badasses and winning unless when they're outnumbered, which is still factual.
Badass Creed: One of the final and most epic parts of Long Live the King.
For their honor!
For their glory!
For the men that fought and bled!
A soldier of Sweden remembers the dead!
Band of Brothers: Union (Slopes of St. Benedict) is really more about this than the Battle of Monte Cassino.
The Carolean's Prayers paints the entire army of Charles XII as this.
Bilingual Bonus: Attero Dominatus uses four words in Latin. “Attero Dominatus” can mean either “Destroy Tyranny” or “Destruction Rules” depending on who you ask, “Denique Interimo” means possibly “Kill at last”.
Gratuitous Latin: "Denique Interimo" is the the only one of those that is, maybe, gramatically correct, meaning "I finally kill". "Primo Victoria" pairs a masculine of neutral adjective with a female noun, and probably mixes up the cases as well. "Attero dominatus" could theoretically be correct if it were intended to mean "I destroy tyrannies", but even then the pronounciation would be off (the stress would have to be on the final syllable, sounding roughly like "ooze" but with a sharp s). Suffice to say John Cleese would have a field day with their lyrics.
"Primo Victoria" might be fine; it's only grammatically incorrect if you're forcing it to mean "First Victory." It could be an adverb with a nominative noun (and an understood "est" if you like), in which case it would mean something like "At first, victory" or "There is victory in the beginning."
And Uprising has one sentence in Polish - “Warszawo walcz!” which means “Warsaw fight!” (imperative, i.e. commanding the city to fight - which it did.)
They constantly use German throught most WW 2 themed songs, although mostly basic terms everyone knows like "Panzer" (using the entire word "Panzerkampfwagen" in Screaming Eagles). In Rise of Evil, which themes Hitler's uprising to power and the development of Nazi Germany, they use words like 'Anschluss' (the annexing of Austria), and 'Lebensraum' (the initial, official motivation for the war). There is also a cover song of Warlock's Für Immer, which is, apart from a bit in the chorus, entirely German. And it is glorious!
"Gott Mit Uns." It's German for "God With Us," and was used a lot in the Thirty Years War.
Carolus Rex in general has a lot of this, with song titles like Gott Mitt Uns and Ruina Imperii (Which is sung entirely in Latin) and whole lines in some songs being in Old Swedish.
Cameo: Actor Peter Stormare and Polish general Waldemar Skrzypczak took a part in making the video for Uprising playing respectively commander of German occupying forces and one of Warshaw Uprising's leaders.
Cold Sniper: White Death, also The Hammer Has Fallen.
Concept Album: Carolus Rex is entirely about the rise and fall of the Swedish Empire from the Thirty Years War to the Great Northern War.
Curb-Stomp Battle: Some of their songs, notably Reign of Terror and Wolfpack, are about these.
Killing Ground is this for the Swedes towards the Russians. The next song on the album, Poltava, reverses their positions.
Dawn of an Era: Lion From The North is about the beginnings of the Swedish Empire under Gustavus II Adolphus. It's very hopeful and energetic. And later...
Death from Above: Firestorm, also Nuclear Attack. Firestorm even drops the trope name:
End of an Age: The general theme of Long Live The King and Ruina Imperii about the fall of the Swedish Empire.
Ghostapo - While Ghost Division is named after the actual nickname of the 7th Panzer Division, the lyrics of the song give the division a supernatural edge by portraying them as a division of both live and undead soldiers fed by the fear the Nazis generate.
Gondor Calls for Aid: "Aces in Exile" is about the air forces of various nations who fought in the Battle of Britain.
Gotter Dammerung: In the bands cover of Amon Amarth's "Twilight of the Thunder God."
Gulf War: Panzer Battalion is about the US armored divisions during Operation Iraqi Freedom, Reign of Terror is about Saddam, his regime, and the 2nd Gulf War itself.
Horrible History Metal: They live by this trope. Most of their songs are about historical events.
'I Am' Song: The song Carolus Rex is this for the titular king.
It Gets Worse: Carolus Rex goes through this quickly, with the hope and glory in songs like Carolus Rex going quickly to the despairing tones of Poltava, signifying the sudden rise and fall of the Swedish Empire itself.
La Résistance: Uprising is a song about the Warsaw Uprising, praising Polish resistance.
From the underground,
rose a hope of freedom as a whisper.
City in despair, but they never lost their faith.
Women, men and children fight,
they were dying side by side.
And the blood they shed upon the streets,
was a sacrifice willingly paid.
Coat Of Arms paints the whole Greek nation as this. Considering how tough the Greeks resisted the Axis in real life, this isn't far off.
Lyrical Dissonance: The Final Solution. An awesome metal song... about the horrors of... well, the Holocaust. Specifically Auschwitz. It's almost impossible to not find the song to be an absolutely glorious ballad from a purely musical perspective, but one still feels very guilty for enjoying it. The band no longer plays that song live because they found it unsettling to see the audience cheer and headbang along.
Price of A Mile as well... also a catchy, badass, upbeat song about.... the soldiers dying pointless deaths at Passchendaele.
Long Live The King is a glorious, epic ballad about... the death of the Swedish Empire and the titular King Charles XII, as his soldiers do everything to bring his body back to Sweden.
Mood Dissonance: The album Carolus Rex goes through this at two points. The first, when after thr triumphant and blood-pumping Gott Mit Uns we go into the Tear Jerker ballad A Lifetime At War. The second when after the hopeful tone of The Carolean's Prayer, Carolus Rex and Killing Ground we get the fast-paced yet noticeably down-turn Poltava culminating in Long Live the King a mournful cry about the death of Swedish glory.
Can't forget The Lion From The North, which is entirely about King Gustavus II Adolphus, the man who kicked basically all of Europe's ass for a few years.
We Burn, regarding the Yugoslavian genocide, although it's written in first person from the villain`s side.
Reign of Terror about Saddam Hussein and his regime.
A Lifetime of War is about how both sides of the Thirty Years War only use the lives of their soldiers for their own gain.
By Kings and Queens young men are sent to die in war.
Their propaganda speaks, their words been heard before...
War Is Glorious: A majority of their songs about World War II are about lionizing the heroes of various nations, especially Poland, Finland and the Soviet Union.
War Is Hell: Angels Calling and The Price of a Mile. Cliffs of Gallipoli also qualifies.
Possibly every song they have and will make about WW 1, because that war was stock full of unreasonable sacrifice for stretches of land you could hike through.
A Lifetime Of War provides two different perspectives on the Thirty Years' War. The English lyrics focus on the horror of the war as a whole and the ambitions of the people behind it, while the Swedish lyrics show it all from the eyes of a common Swedish soldier who leaves his friends and family behind to serve his nation with no guarantee if he will ever return alive, or if he will be remembered and mourned.
Warrior Prince: King Charles XII of Sweden, as per real life.
World War II: One of their common themes, as many battles they sing about took place in that time period.