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.
In fact nearly every track on the album opens with a woman reading excerpts from The Art of War.
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 except when they're outnumbered, which is still factual.
Badass Boast: Carolus Rex is this for King Charles XII of Sweden. In contrapart, Poltava counts as this for The Tsar Peter ("Listen, excuse for a king! Trust me, this fight you can't win!")
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” most likely means “I Destroy Tyranny”
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 WW2 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 apart from a part of the chorus that's in English and Spanish, is entirely in German.
"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 Mit Uns and Ruina Imperii and whole lines in some songs being in Old Swedish. Plus, there is a Swedish Version of the whole album. Ruina Imperii is the only song on the album that doesn't have an English version, not counting bonus tracks.
The "chanting" in The Carolean's Prayer is the Lord's Prayer in 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.
Killing Ground is this for the Swedes towards the Russians. The next song on the album, Poltava, reverses their positions.
Dark Reprise: While the lyrics certainly do not reflect it, Ruina Imperii is this to Lion From The North, both when you notice that the chorus of the first is more or less a very downtrodden version of the other, and that while Lion From The North covers the rise of the Swedish empire, Ruina Imperii covers its fall.
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.
Death from Above: Firestorm, also Nuclear Attack. Firestorm even drops the trope name:
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.
Saboteurs is about the Norwegian resistance fighters sent to destroy the Telemark heavy-water plant.
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.
Mondegreen: From "Panzer Battalion", "DEATH IN THE SHAPE OF A HANDSOME ITALIAN!"
Mood Whiplash: 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 and Ruina Imperii - mournful cries about the death of Swedish glory.
Number of the Beast: Played for Laughs by "A Secret" which contains a part that says that it has detected an illegal download and is executing spyware protocol 666. Note that 666 is spelled out at "Six hundred sixty-six."
The album cover for Heroes shows an American soldier punching a nazi soldier in the face so hard that the latter is sent flying.
Recruiters Always Lie: In "In The Army Now", the recruiter says that Army doesn't do much except stay in bed, and that the recruit will be a hero to the neighborhood. Nothing like it happens; he's thrust into a war and nobody really cares about him.
Title Drop: Aside from “Metalizer”, evetry song that shares a title with their albums has one. Multiple other songs too.
Trolling Creator: Their song "A Secret" from The Art Of War begins with another excerpt from The Art of War, but a short time later plays a computerized voice speaking in English that an illegal download has been detected and that spyware is to be activated. This happens on all versions of the album, which makes it particularly funny when it happens on a Compact Disk being played in a Walkman.
Exact Words: "Hostile armies may face each other for years, striving to the victory which is decided in a single day." Several silent seconds later: "Illegal download detected, executing spyware protocol 666" It's pronounced as "six hundred Sixty-Six"
Villain Song: Well, more like "Antagonist Song" as the album doesn't paint them as villains: "Carolus Rex" is entirely told from the perspective of the Swedish Empire and its kings, with the single exception of Poltava, which is sung from the perspective of the Russian Troops and their Tsar gloating about how they trounced the Swedish Troops at Poltava.
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 WW1, 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.