This is perhaps more suited to something like /r/AskAcademia or /r/GradSchool, but I was curious to see what folks on here have to say.
For those who work in European history--whether preparing for grad school, or ABD, or tenured--which languages (apart from English) do you draw on the most?
For those in 18-20th-C European history, I've a more personal question: would you find Spanish or Italian more useful? Context is that I'm about to enter grad school in 18th-19th French history, and have French, German, and Latin, but am juggling between moving on now to either Italian or Spanish. My thinking is Italian--assuming it was more dominant during the Enlightenment and 19th C., with Spanish more suited for the early modern period--but I'm interested to hear what others think.
I am an Americanist but sometimes use German and has a minor field in European history. 19th century German-American immigration to the United States is one of my preferred areas of research. 99% of my research is done in English.
My university has a huge number of Napoleonic historians due to a research institute located here. Thus, if you entered it your choice of language would depend on what location and time period you wanted to study in most depth. For the Peninsula War, Spanish would be preferred. For the Italian Campaigns, or perhaps when dealing with Napoleon III, Italian might be more fruitful.
Most schools wouldn't require more than three languages for a PhD in European history, so don't feel compelled to learn more than required. You will have your hands full with plenty in your tenure. I suppose if you have mastered those languages already it cannot hurt to pick up another.
Let me know if you have any other questions.