Final answer:
World War I was the major event that profoundly influenced the modernist movement, fostering new artistic and cultural movements and leading to a significant shift in societal values and structures, embracing the ethos of making it new.
Step-by-step explanation:
The major world event that had a profound influence on the modernist movement was World War I. The war and its resultant social and political turmoil spurred the desire for a radical break from the past, compelling artists, writers, and thinkers to push the boundaries of creative expression. Modernism is characterized by a variety of movements, including Cubism, Dada, and Surrealism, which incorporated unprecedented styles and techniques, such as collage, and took advantage of new technologies like cinema.
The war-induced trauma and the disillusionment that followed were critical in shaping the modernist ethos, which was reflected in the mantra "Make It New!" advocated by Ezra Pound. The era saw a significant questioning of traditional structures and a move towards a reimagination of societal standards in political, religious, economic, and social realms. This period was marked by tremendous growth and innovation, as well as a general skepticism towards previous norms and conventions.
The tumultuous events of World War I, supplemented by the rapid growth of cities and the development of industrial societies, set the stage for modernist ideas to bloom in various fields, such as art, architecture, literature, and even sciences, revolutionizing the cultural landscape of the time.