How should I write an essay titled "Love and War in Troilus and Cressida"?

In writing an essay on this theme, the first thing to consider is that a subject area is not the same as a thesis. The two main plots in the play, the love between Troilus and Cressida and the conflict between the Greeks and Trojans, are respectively concerned with love and war. Saying that one will write about "love and war in Troilus and Cressida" really is just saying that one will discuss the play in fairly general terms. An essay, however, needs to be more focused and needs to make a specific claim about some aspect of love and/or war, rather than simply summarizing the main elements of the play. 
One interesting feature of the play is that it emphasizes the connections between the Greeks and Trojans far more than its sources. The plot of the young lovers is actually a medieval innovation and the connections between Greeks and Trojans in Shakespeare are far closer than those found in the Iliad. Thus, one interesting way to narrow your focus might be to explore how love and conflict are not merely two separate themes expressed in the two plots of the play; instead, you might posit that the uneasy relationship between the two young lovers is a microcosm of the relationship between the Trojans and the Greeks, who are portrayed almost as quarreling lovers but are bound by ties of friendship and kinship in a devastating war of pride and anger.
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