I could recommend the War of the Austrian Succession, a time when Frederick the Great came out of nowhere and gave Europe a dose of Prussia, allowing Prussia to become the major power it became. Further, it isn't a very well known compared to other major political events.

Everyone here is going to be biased toward their own field, because who does THAT much reading about something they find dull? We need to know what you find interesting, because it's your interest in the essay that matters. Given your examples, I'm guessing you like military history, as political events aren't always linked to military actions and you've named two from very different time periods. So are you interested in situations in which one group overthrew another? If so, the Glorious Revolution might fit the bill (this is also the genesis of the Jacobite movement I'm so fond of). Is there a particular country or part of the world you're interested in? For that matter, what are some of your own interests? It's surprising how many things relate to politics.

In any case, if you give us a bit more information by answering these questions, you'll be more likely to get a response that suits you. I'd recommend putting your answers in the OP rather than replying to me, so newcomers to the thread see them, when they might not read all comments.

Finally, you might take a look through our user profiles, as they contain links to questions some of our flairs have answered. You might find a mention of a suitable event there.

I would advise caution if you take on the Spanish Civil War. It is a highly complex topic, including nearly all the major actors of WWII, multiple competing political systems, and a somewhat confusing chronology of events. Now, taking a part of the Spanish Civil War could be quite interesting. Perhaps you could find a group or movement that you have some affinity for and look at their role during the war. If you're Catholic, the Basques could be interesting, as would be the Carlists. If you're a leftist, then the communists or anarchists could be fun to look into. If you're a big fan of local government over national government, then the Basques, Catalans, or Galicians could be very interesting for you. You specify a 'political event', so I don't know if the military events like the bombing of Guernica or the Battle of Guadalajara would qualify.

If you decide on an aspect of the Spanish Civil War as your topic, I would be happy to point you towards a number of books on the subject. To get a contrasting perspective, /u/tobbinator is an expert on the Republicans (while my research focused on the Nationalists and the Basques).

leadup to WW1, WW2 or all the wars.

Chinese Revolution, Russian Revolution, French Revolution.

The situations of the South American nations in the 2000s

Europe after WW2

The Balkan states post WW1