Origins of the war:
Habsburg monarchs dominated the Balkans. Our brothers of the same faith were under heretic rulers. At first they favoured papacy and then they start constructing their own heressies. People were tired by the heretic movements.
Moreover, Habsburg monarchs claimed to be the legitime continuation of Roman Empire! They called their kingdom "holy roman empire", although they weren't neither holy or roman. Russians didn't forgot that they had this extraordinary claim even when Byzanium was alive. Russians show themselves as the true continuators of both christianity and romans. Moscow was known as "third Rome", and the patriarchate of Kiev, was the strongest orthodox stronghold.
Later historians realised the importance of Konstantinopolis. The city was one of the most important economic centers in Europe that time.
Last, Habsburgs monarchs dominated Europe in the west as well. Spain and south France were occupied, the papal states were indepedent only de jure. Russia realised that Habsburgs were a major threat to Russia and european balance.
Moreover, Russians discovered new military tactics and advanced mounted weaponry. It was a matter of time to see a russo-german war.
Peter ordered the reformation of the army. Most russian citizents were orthodox christians, so he asked for church's help and blessings. Fanaticism spread across the tsardom, but it was very effective. People were persuaded about the importance of this war and joined the army readily. Moreover, the people of the conquered cities would favour their new monarch more.
In 1575 Peter declared the holy war against the Habsburg rule in Balkans. Russian army moved from Lwow to Budapest and the battle begun.
First battle of Budapest:
Russians surprised Germans. Buddapest fell in few months with minimal losses.
Battle of Konstantinopolis:
Russian moved quickly deep in german territory and liberated Konstantinopolis! It was a great victory. Peter wanted to keep this city from now on whatever the cost will be. Orthodox populations celebrated that the only orthodox tsardom was here to protect them.
Second battle of Budapest:
After the initial sock Germans organised themselves and conducted a counter attack to recapture Budapest. This was the most important battle in these wars, and would decide the final outcome. Germans built their camp just near Budapest. Peter didn't wait for the counterattack, so he attacked the camp. Bombards devastated the camp.
The battle devastated both armies. Russia kept the city and the new armies trained in the motherland would support further the war. Unfortunately, Peter himself died in this battle. Generals buried him with all honours and continued the war.
Battle of Beograd:
The mountainous region of Serbia costed a major loss, but Serbia was liberated.
End of war and outcome:
Although Russians seemd to win the war, the army was severely damaged and couldn't continue. Habsburg monarchs paid war conmpensations and peace was declared.
After peace, Russian people starting celebrating. The festivites took place for many months.
Russia was a great mulinational kingdom and the most important kingdom of its time at last. It was declared an
empire.
Serbian mines produced large amounts of copper. Russian economy could invest in bronze at last.
Russia managed to accomplish only one objective of what was desired. They didn't even managed to capture Derbent! However, the tsardom gained control of Serbia, Bulgaria and Tracia. Balkans were rich and gave a great boost to economy, especially Konstantinoplis was a great port. Russians managed to increase research funding by 10%. Royal treasury filled due to spoils of war.
German military took a major and unforgetable hit.
Other geopolitical events:
Dutch took advantage of the war and declared their indepedence from Habsburg monarchs. Peter (he was alive then) recognised the new state.
Polish citizents of Lwow took advantage to organise an uprising. Fortunately it was unsuccesfull.
Germans were weaker, but French power increased dangerously. Louis (all french monarchs called themselvs Louis) didn't hesidate to ask for tribute! Maybe the new threat were the french? At least Russia was more important.