What is the major conflict of the play?
The largest conflict in August Wilson's Fences is Troy's internal conflict, which could also be termed as Troy's conflict with Death, a character that exists in Troy's stories, usually appearing in his most emotionally turbulent moments.
Death ain't nothing but a fastball on the outside corner.
In the beginning of the play, Troy talks about wrestling with Death as his friend Bono and his wife Rose listen to him one evening after work, and they laugh him off as being silly or drunk. He recounts a time in which he was hospitalized and sick, and Death came to him:
Death stood up, throwed on his robe...had him a white robe with a hood on it.
This is certainly a reference to KKK robes, an obvious threat to life in the black consciousness. Rose and Bono give Troy casual glances to acknowledge the reference, but they still laugh and dismiss Troy's outlandish storytelling.
However, as the play goes on and the external conflicts are introduced, Troy's flaws and anxieties become magnified and he begins to again address Death, daring the character to come and wrestle with him again. Here it becomes clear that the biggest threat to Troy's life is his own destructive tendencies, tendencies that have been developed over a lifetime of having to fend for himself and take what he can. When his extramarital affair ends in the death of his mistress during childbirth, Troy begins to recognize that his life's arc is sloping downward:
All right...Mr. Death....I'm gonna take and build me a fence around this yard. See? I'm gonna build me a fence around what belongs to me. And then I want you to stay on the other side. See? You stay over there until you're ready for me.
Here, Troy is bargaining for the life of his family members, noticeably excluding himself from the deal, saying Death can cross the fence only to get to him. Death, of course, is a character in Troy's head as much as it is a reality of human existence, so the fears of Death the character and Death the actual end of life are both internal conflicts within Troy.
Troy's story of wrestling with Death also stands as a metaphor for internal conflict:
Then you [Death] come on. Bring your army. Bring your sickle. Bring your wrestling clothes.
We use phrases like "wrestling with guilt" or "wrestling with big decisions" to describe everyday internal conflicts that people experience, but in the play the motif of Troy wrestling with Death stands as a constant reminder of Troy's internal struggles, which drive the major events of the play.
In Fences, the major conflict is not between white and black, husband and wife, or old and young. Although all of these conflicts exist, the main conflict is between Troy and his internal and external "fences" (the limitations which keep him from achieving his dreams, opportunities, financial goals, interpersonal relationships, and self-image).
As a period piece about a working-class family in Jim Crow America, Fences pits the individual against personal (dreams), social (racism), economic (back-of-the-truck status), and institutional (church, military) limitations. Troy is drawn-and-quartered between all these limitations and, yet, he keeps getting burdened with more responsibilities within the family (more mouths to feed, his son's future, his brother's mental care, etc...). It's enough to make a man burst, literally and emotionally.
By the end of the play, Troy is dead and all of his family are "fenced off" in institutions: Gabe in the mental institution, Lyons in his music, Rose in the church, Cory in the military. Only Raynell, his illegitimate child, ironically, is not fenced off and burdened. She is Troy's legacy and symbolic of the next generation's hopes and dreams.