The great turkish war goes much deeper than the smoke of field guns, war cries of janissaries and thunder of the polish cavalry in 1683. It was the climax of border tension and ottoman intervention in europe to understand why the ottomans found themselves toe-to-toe with an entire holy league of nations
Vienna was of course an obvious target for ottoman expansion against an enemy it had proven more powerful than. A large hub of culture and trade the reward and pillage would be astronomical not to mention the message it would send to the papacy and all of europe
Sobeyevsky attempted to push the advantage with a coordinated counter-attack into the ottomans hegemony in hungary but it would fail to come to fruition. The ottomans would do their best to avoid major battles and instead harass the christian army, but resulted in over extending themselves leading to their fall.
The unusual disease that came out of nowhere ravaged the world and disappeared humanity has been fighting diseases as long as humanity has existed but spanish flu is quite unique as the world population grew and we became more interconnected throughout history. We fought bigger and bigger pandemics however we learned how to urbanize long before we ever learned how to properly fight these diseases.