As far as we know Youjo Senki is an alternative world of our world right? But with magic. I think history changed since 'French revolution' which was take place in our world 1781-1798, in Youjo Senki 1788-1805, since WW1 in Youjo Senki is 7 years after ours world. I have no Idea when magic was discovered here but probably since ancient times obviously. In 1805 Bonapate raised on power becoming council. (in our history is 1798, in 1803 he became emperor). Battle of Austirlitz happened in 1812 here and Rus' campaign in 1819 where he failed... In 1821 Bonapate surrendered and Paris taken by Rus', Prussian (most likely called like that) and Austrian armies. (1814 in ours) and Waterloo happened year after.
After Napolionic wars in Europe everyone in piece. Until 1860's-1890's when Otto Von Bismark (100% in Youjo Senki his name is changed) declared war on Denmark, taking it and taking a small part of Sweden, here Norway, Sweden unites again. In the same time German unification is taking place AND Austria also unites with Germany and from now on we have - 'Empire' But I'm questioning my self, how the hell Empire have rest of Poland in their control? Since that 2/3 of Poland was on control since 1770's by Russia (Rus') did they fought each other? I don't think so, since in second half of 19 century Russia and Germany were friends, maybe Russia gave those territories to Empire after Cramean war? I don't know. In 1880's (in our world 1870's) Franco-Prussian war take place. Around this time unification happens. And Netherlands with Belgium also unites... Why? Dutch don't have any reason to do so... Ok it happens in Youjo Senki...
Summary The main protagonist Tanya is a young blonde blue-eyed girl who is the reincarnation of a Japanese Salaryman. Due to her refusal to believe in God and encountering a figure, who she dubs X instead of God, she was sent into a fantasy realm of the current verse's setting. Youjo Senki is the story about a young little girl, Tanya Degurechaff, nicknamed 'Mitril' living as one of the loyal soldier of Empire. She was originally a 40 year old salaryman killed by his fired personnel in their company. Now, he was reincarted by God as a young beautiful and sarcastic little girl.
In 1912 battle of Tshusima happens, same year Rus'-Japanese War is over.
In 1919 Titanic sunks.
And in 1922 WW1 starts, how it's starts? In our world Duke Franz Ferdinand is killed his - Austrian. In Youjo Senki Austria is no more... (really I have no Idea how war starts here.)
But I mean, emagine a country with many ethnic groups, people etc. With their own language, laws, culture etc. Very close country in our world is Hapbsburgs also known as Austria-Hungary which had problems about it becouse there was every body in the army and soldiers couldn't understand their officers and their comrades since they slav, German or anybody else. Same applies to Empire in Youjo Senki...
Culture (Names discussion)
Did you know that - Tanya is actually Russian name? But Tanya have Prussian/Saxon familyname, let's analyze - her dad is most likely Prussian, in episode 3 she says that her dad was soldier and he died (atliest how I understand it) and her mother is Slavic: Chech, Pol, Rus' (Russian) etc. But most likely - Rus' since name 'Tanya' (Таня) is very popular name there. So she's half Prussian half Russian.
Next Victoria Ivanovna Serebryakov
-> Victoria name of Slavic origin, this name became very popular in rest of Europe in mediaval time. Proof of this (not mediaval though - Queen Victoria British Queen since 1820-1901).
-> Ivanovna, In Slavic countries, especially Russia, Ukraine, Belarus, there's 2nd surname which marks father's name (Female Ivanovna, Male - Ivanovich) Visha's dad name - Ivan, extremely popular name In Russia.
-> Family name - Serebryakov also Slavic origin. Usually in Slavic nations family name have some adentical by roots for example: Shashkov, root Shashk- close word to it Shashka (Шашка) Shaska is Cassack sword/Saber, Kobzar' root word Kobzar' (Кабзарь) - this is Slavic music instrument (very close to guitar) also is name of Taras Shevchenko book, Pushkin - root word Pushk- Pushka (Пушка - cannon (artillery piece)) Back to Serebryakov root of this family name - Serebryo (Серебро - Silver)
Conclusion Visha Is either Rus' but Empirial either she half Prussian and Half Rus'.