An epic. Epics are often long, narrative poems that tell the story of heroic deeds, adventures, and great events. They usually involve heroic characters who overcome significant challenges.
A heroic chronicle. A chronicle usually refers to a record of events, and when it's a heroic chronicle, it means a record of heroic events. It might be a story that is written in a more matter - of - fact way compared to an epic, but still highlights the heroic deeds and the people who did them. For example, a local town might have a heroic chronicle about a hero who saved the town from a disaster that is not widely known outside of that area.
Well, 'the commencement' is another way to refer to the start of a story. It's like the story is about to commence, start its journey, and draw the reader in from that very first moment.
The start of a story can also be called the 'opening'. For example, in many novels, the opening sets the scene, introduces the main characters or gives a hint about the main conflict.