In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
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Question: One party in this conflict was led for part of it by the namesake of a battleship famous in a later conflict, the Duke of Caxias. This clash was precipitated by the ouster of Atansio Aguirre. Victory at Curupayty forestalled defeat for the eventual losers, whose fate was practically sealed after the naval Battle of Riachuelo. This war's namesake treaty was the brainchild of Bartolom Mitre, who favored the Colorado Party over the Blanco Party in Uruguay. FTP, name this conflict in which Paraguay under Francisco Solano Lpez was eventually defeated by the namesake entity, consisting of Argentina, Brazil, and Uruguay.

Answer: History

Question: Ninhydrin forms a Schiff base with this chemical, resulting in a hue known as Ruhemanns purple. The Birch reduction takes place in a liquid substrate of it, the reason it is common in methamphetamine labs. The Kjeldahl method uses this molecule as an end-product to measure the amount of nitrogen in a sample, and it is oxidized in the first step of a nitric acid forming procedure, the Ostwald process. For 10 points, name this weak base found in fertilizers, formed by combining hydrogen and nitrogen in a three-to-one ratio in the Haber process.

Answer: Science

Question: This effect dominates in energy regimes under one mega-electron volt, while at higher energies Compton scattering and pair production are likely to occur. It was first observed by Heinrich Hertz while working with spark gaps. Mathematically, this effect is likely to occur when the threshold frequency of the electromagnetic radiation times Planck's constant is equal to the work function, usually represented by a lower case phi. For 10 points, name this effect where incident light on the surface of a metal releases electrons.

Answer:
Science