Asserting a claim means advancing argumentation by backing up reasonable arguments. It is a distinctive activity that requires a certain amount of intelligence. According to Searle (1969: 66), the act of asserting a claim or giving reasons is called arguing. In spite of the research presented for understanding the argumentative function of the language, the factors affecting the composition of an argumentative text varies according to several linguistic features. Thus, this study deals with the act of arguing in a political narrative from a pragmatic perspective. Just so, this study attempts to answer two main questions that have the same scope: (1) What are the pragmatic realizations of the act of asserting in narratives? And (2) What is the significance of the illocutionary force of assertive speech acts in advancing argumentation in written texts? The corpus of the study consists of some selected dramatic passages of Remarque's political novel with common English publication by Fawcett Crest. In answering the study questions, it is hypothesized that (1) the act of arguing in written texts, more specifically in political narratives, usually takes the form of an assertive, (2) a great coherent communicative force is best viewed in the illocutionary force of this act that leads to effective perlocutionary effects. In order to reach convincing results proving the hypothesis, a qualitative descriptive approach is developed for the analysis of the data relying on observation and introspective reading.