War The Nigerian Civil War (or the "Nigerian-Biafran War") started on 6 July 1967 and ended on 13 January 1970. The war broke out due to political and ethnic struggles, partly caused by the numerous attempts of the southeastern provinces of Nigeria to secede and form the Republic of Biafra. Political conflict between the Igbo, Yoruba, Hausa and Fulani people erupted into two deadly military coups. The Igbo tried to breakaway from Nigeria to become the Republic of Biafra, but was met with little support. From 1968 onward, the war fell into a form of deadlock, with Nigerian forces unable to make significant advances into the remaining areas of Biafran control. Nigeria cut off humanitarian aid to Biafra, resulting in hundreds of thousands of civilians dying from starvation and disease. Many lives and resources were lost during the war; and even today there are still tensions between the different ethnic and religious groups of Nigeria.
The story in Half of a Yellow Sun centres on the war. The author has stated she believes that many of the issues that caused the war remain today. She further commented that the war is talked about "in uninformed and unimaginative ways", and that the war is as important to the Igbo people her book features today as it was then. Because none of the major political events were changed in the book, Adichie said that the book contained "emotional truth", and that the book showed the war had a significant impact upon the people of Nigeria.
Politics and identity in post-colonial Africa The social gatherings at Odenigbo’s house are full of debates on Africa’s political future. Here, the usefulness of various forms of African governance are discussed amongst the Nigerian intelligentsia. One particularly noteworthy debate involves Odenigbo defending the tribe as the ideal unit for African, as other characters stress the need for pan-Africanism or nationalism. He is quoted as proclaiming: “the only authentic identity for the African is the tribe...I am Nigerian because a white man created Nigeria and gave me that identity. I am black because the white man constructed black to be as different as possible from his white. But I was Igbo before the white man came.”
Role of Westerners in post-colonial Africa Although there is a clear accusation of Western influence on Biafran war (mostly England’s involvement in the war), a more subtle critique is found in Richard’s character. Richard, although with good intentions, tries too hard to be part of first Nigeria, and later Biafra. His fascination with the culture and his wish to be part of Biafra leads to him speaking for Biafrans by attempting to write two novels, one about the art, and the second one about the Biafran war. Richard is unable to complete either, and concludes that these are not his stories to tell. However, he is effective when he writes about the war for the Western press, which actually helps Biafra’s cause. Adichie herself has said in an interview, that “maybe [Richard’s character] is my subtle way of slipping in my politics that maybe it’s time that Africans wrote about Africa.” 
Relevance of academia in everyday life Many of the main characters in Half of a Yellow Sun are professors, including Olanna and Odenigbo. Odenigbo regularly hosts fellow professors from Nsukka University for political discussions on the weekends. Over the course of the novel, Half of a Yellow Sun seems to criticize both these professors and their opinions. It does this by juxtaposing the high-minded political opinions of Odenigbo and his companions from the “Early Sixties” sections against the political realities of the “Late Sixties” sections. The novel also uses the same professors from the “Early Sixties” sections and puts them in the “Late Sixties” sections. Also, Kainene’s business mind helps her successfully run a refugee camp, whereas Olanna and Odenigbo seem ineffectual. Adichie seems to emphasize the reality of action over the ephemeral nature of opinion.
Rule of Western journalism Half of a Yellow Sun is heavily critical of the Western media's coverage of the Biafran War. The rule of Western journalism is obvious when Richard meets with the foreign journalists: "Richard exhaled. It was like somebody sprinkling pepper on his wound: Thousands of Biafrans were dead, and this man wanted to know if there was anything new about one dead white man. Richard would write about this, the rule of Western journalism: One hundred dead black people equal one dead white person." Since it is clear that white journalists have a greater influence, Madu asks Richard to write about the war for the Western press: “They will take what you write more seriously because you are white. If you really want to contribute, this is the way that you can. The world has to know the truth of what is happening, because they simply cannot remain silent while we die.”
Women empowerment Although Half of a Yellow Sun does not have the conflict between a woman and patriarchy typical of feminist novels, it does show the agency of women. In one of the pivotal moments, Olanna is disappointed by Odenigbo’s betrayal and goes to Kano to seek comfort from her family there. Aunty Ifeka says: “You must never behave as if your life belongs to a man. Your life belongs to you and you alone.” Later on, even after forgiving Odenigbo, she confronts him about his betrayal and does not accept him justifying his actions by blaming his mother. On the other hand, when Olanna's father cheats on her mother, Olanna's mother does not confront him about it. She only asks Olanna to tell her father to do it more subtly.
Marriage Marriage is a recurrent theme in Half of a Yellow Sun. For the most part of the novel, Olanna and Kainene both live with men without it being question of marriage. Olanna refuses to get married many times at first, fearing that marriage would “flatten [their bond] to a prosaic partnership." It is only during the war, when Odenigbo is invited to a town meeting in Abba and Olanna is not, that they talk again about marriage. Olanna accepts, but the wedding is done hastily and is interrupted by an air raid. Although Richard never asks Kainene to marry him, he does mention his wish for her to be his wife many times. Arize who is poor and uneducated, admires Olanna for postponing marriage but waits eagerly for a husband herself: “It is only women that know too much Book like you who can say that, Sister. If people like me who don’t know book wait too long, we will expire.” Adichie seems to be saying that marriage is a pragmatic choice and women who don't need to get married might chose not to even when their boyfriends are willing.