Abyssus abyssum invocat

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

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

Chapter I: Rapid advance
Tanya's Salamander Combat Group (SCG) is sent to the Eastern front. There she fights against Union forces, and in one engagement she captures some prisoners of war. Using her linguistic skills as an emigre from notRussia, Visha unofficially interviews some of these prisoners and learns that the Union 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 Union territory, the more the enemy will resist and fight harder.

Of course Tanya also remembers that the Union 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 Union 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 Union.

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

At Moscou, under Loliya's orders, the Union also decides to increase cooperation with the UK 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 Union and the UK. And he will send idealistic communists to the UK 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 SCG is ordered to return to the capital immediately.

At the General Staff office, General Ruderdorf gives Tanya a new medal, the White Winged Grand Iron Cross. He also informs her that they are dismantling her SCG. Tanya is extremely upset by this, but Ruderdorf 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 Ruderdorf orders her to go back to the Norden with her 203rd Aerial Mage Battalion and attack the new supply route linking the UK and the Union. In the meantime the General Staff will organize a new combat group for Tanya.

[As a side note Lt Colonel Ugur and Tanya meet fairly often when Tanya or the 203rd takes the train because Ugur 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 UK and the Union.

When the 203rd, an over-strength battalion, attacks the Queen of Anjou, a regiment of UK 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 Union dock, she decides to strike.

Chapter V: Timeout
Union 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 UK mages and Mary Sue. Col Mikel and Lt Col Drake become friends.

Meanwhile Tanya's 203rd is boards a submarine and heads to the Union 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 Union military capture her. A new political commissar is sent to Col Mikel, Liliya Ivanova Taneechika (an idealistic communist). While Mikel and Lt Col Drake hates political commissars in general and Taneechika 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 Aarens of the Tank battalion seems competent. But she finds 1st Lt Rolf Mehbelt of the artillery company to be too set in his ways, and Captain Reinhardt Tone and 1st Lt Claus Tospan of the infantry battalion to be morons. Finally the new company mage recruits led by 1st Lt Teobalt Westeman can learn and are willing but they are too inexperienced. Thus Tanya decides to keep the 203rd as a regular battalion and use Westeman's company as a separate company.

While the new Salamander Combat Group is training, the Union attacks. Chaos ensues, Captain Tone keeps disobeying Tanya's orders and goes on a recon mission without telling anyone. Eventually the SCG defeats the enemy. Tone 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"
UK and Union alliance seems to be going well. At least Loliya is satisfied. While he can't fool any of the diplomats or high ranking government officials, sending in idealistic commissars to the UK is having the effect he intended. Many ordinary people and ordinary soldiers in the UK 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 Union 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.