Abyssus abyssum invocat

Abyssus abyssum invocat is the 5th volume in the Youjo Senki Light Novel series.

Short Summary
The power of blessing emerged in the surface.

Tanya and Mary sue have faced one another.

Who shall prevail?

Chapter O: Letter to the home
A short letter from Mary Sue to her home.

Chapter I: Rapid advance
Tanya's Salamander Kampfgruppe is sent to the Eastern front. There she fights against Federation forces, and in one engagement she captures some prisoners of war. Using her linguistic skills as an emigre from Russy Federation, Visha unofficially interviews some of these prisoners and learns that the Federation soldiers are fighting to defend their homeland. When Visha informs Tanya of this, Tanya is shocked. She realizes that she is now fighting against nationalists and immediately recognizes that this is a major problem. Because this means that the more the Reich wins and invades Federation territory, the more the enemy will resist and fight harder.

Of course Tanya also remembers that the Federation is actually a multi-ethnic state and therein lies her one chance.

Chapter II: Strange friendship
Tanya returns to the capital to inform Zettour that they are not fighting communists, and that the ordinary Federation soldiers are motivated by nationalism. And so her recommendation to Zettour is that the Reich needs "good friends" who will help the Reich by fighting for their own independence. This means forming "national committees" and delegating police powers to the various ethnic minorities of the Federation.

Meanwhile the Commonwealth decides to send aid to the Federation. The Commonwealth will send mages (remnants of Mary Sue's US volunteer expeditionary force are placed with Lt. Col Drake's marine mage units) to the Federation as a symbol of their cooperation. The Commonwealth also wants the US to get involved but popular opinion in the US is still against the war. Finally, the Commonwealth decides to open a new supply route from the Commonwealth to the Federation by using a massive ocean liner that is faster than a submarine. [Commonwealth to Murmansk or Commonwealth to Archangel not clear which.]

At Moskva, under Loria's orders, the Federation also decides to increase cooperation with the Commonwealth and appeal to the rest of the world that their alliance is real. To do this, he decides to exchange prisoners/intelligence agents between the Federation and the Commonwealth. And he will send idealistic communists to the Commonwealth to woo public opinion.

Chapter III: Northern operation
[Tanya hits her 13th birthday on Sept 24, 1926.]

Tanya had returned to the Eastern Front after her talk with Zettour, but she and the kampfgruppe is ordered to return to the capital immediately.

At the General Staff office, General Rudersdorf gives Tanya a new medal, the White Winged Grand Iron Cross. He also informs her that they are dismantling her kampfgruppe. Tanya is extremely upset by this, but Rudersdorf reminds her that the combat group was supposed to be an adhoc entity. And that the General Staff needs to learn how to organize other combat groups without using Tanya.

So Tanya has no choice, and Rudersdorf orders her to go back to the Norden with her 203rd Aerial Mage Battalion and attack the new supply route linking the Commonwealth and the Federation. In the meantime the General Staff will organize a new combat group for Tanya.

[As a side note Lt Colonel Ugar and Tanya meet fairly often when Tanya or the 203rd takes the train because Ugar is working for the railroad department. Or when they are in the capital. And so their friendship becomes real.]

At one meeting with Ugur, he informs her that her new mission to Norden is the result of the Reich's intelligence service. And not something the General Staff necessarily wants to do. As an apology Ugur has obtained reservations for the 203rd at the officer's club. Unfortunately the bouncer of the club won't let Tanya in because she is a minor.

In the former Entente territory, the 203rd sets up a new base and starts to look for this new supply route. There they find the giant ocean liner, the Queen of Anjou. It's huge but sails so fast that the submarines can't catch her. And because it's huge, it carries a ton of cargo between the Commonwealth and the Federation.

When the 203rd, an over-strength battalion, attacks the Queen of Anjou, a regiment of Commonwealth marine mages greet Tanya and combat ensues. Since the 203rd was already flying for a long time, and because it is heavily outnumbered, the 203rd fares badly. Also Mary Sue attacks Tanya ferociously.

After the 203rd finally returns to base Tanya hears of the damage report and reacts with simmering anger. She hates that she has lost many of her elite troops because it's a waste of resources. When her men sees that, they become more loyal to Tanya because they think she is grieving.

Chapter IV: Long range assault operation
The General Staff gives new orders to Tanya. Once new recruits to replace the lost veterans arrive, the 203rd is to go to the Eastern Front and form into a new combat group.

But before that, when Tanya learns that the Queen of Anjou is in a Federation dock, she decides to strike.

Chapter V: Timeout
Federation mages are deployed to defend the Queen of Anjou, docked at Novo Holmo. Led by Colonel Mikel (who used to be in a gulag), they are joined by Lt Col Drake's Commonwealth mages and Mary Sue. Col Mikel and Lt Col Drake become friends.

Meanwhile Tanya's 203rd is boards a submarine and heads to the Federation dock. 2 companies launch from the submarine and surprise the defenders while 1 company blows up the Queen of Anjou.

When Loliya hears of the news, he is not angered but rather filled with joy. He is elated that Tanya is still alive and he redoubles his efforts to help the Federation military capture her. A new political commissar is sent to Col Mikel, Liliya Ivanova Tanechka (an idealistic communist). While Mikel and Lt. Col Drake hates political commissars in general and Tanechka is not an exception, Mary Sue becomes friends with Liliya.

Tanya is now at the Eastern Front with her new combat group and she is in low spirits. She thinks that her new colleagues are mostly useless. Captain Elmer Ahrens of the Tank Company seems competent, yet she finds 1st Lt Rolf Meybert of the artillery company to be too set in his ways, and Captain Lienhart Thon and 1st Lt Klaus Tospan of the infantry battalion to be morons. Finally the new company mage recruits led by 1st Lt Theobalt Wüstemann can learn and are willing but they are too inexperienced. Thus Tanya decides to keep the 203rd as a regular battalion and use Wüstemann company as a separate company.

While the new Salamander Kampfgruppe is training, the Federation attacks. Chaos ensues, Captain Thon keeps disobeying Tanya's orders and goes on a recon mission without telling anyone. Eventually the kampfgruppe defeats the enemy. Thon is MIA.

During the battle Tanya comments that she wants Visha's coffee and everyone laughs. They hear it as a confession of love. Tanya debates romantic implications for the first time. If she dates a man that makes the physical relationship heterosexual but mentally homosexual. If she dates a woman that makes the physical relationship homosexual but mentally heterosexual. She can't decide. Because it's in the middle of combat, Tanya stops thinking about this and gets back to war.

On October 20th, the day after the battle, it snows. Winter has arrived.

Chapter VI: "Liberator"
Commonwealth and Federation alliance seems to be going well. At least Loria is satisfied. While he can't fool any of the diplomats or high ranking government officials, sending in idealistic commissars to the Commonwealth is having the effect he intended. Many ordinary people and ordinary soldiers in the Commonwealth are beginning to feel sympathy for the communist cause.

On November 24th, 1926, Hans von Zettour makes a speech declaring that the Reich does not demand territory and that it plans to help new nations become independent and to continue the fight against their common enemy, the Communists. That day the military relinquishes control over civilian administration in conquered Federation territory to the newly formed nationalist organizations.

That ends 500+ pages of vol 5.

Thanks to u/MSG_Johnny2 who posted the summaries at r/YoujoSenki.