In telling his story aboard the ship on the Thames, Marlow reveals how he got his job as the captain of a steamship.
Accordingly, he had just returned to London after several assignments in the East. He visited his old friends and spent time socializing. After enjoying a period of rest and relaxation, however, Marlow began to yearn for new adventures.
It was during that time that he remembered his childhood fascination with far-off, unexplored regions. To his recollection, these places intrigued him. When he grew up, the rivers and lakes of these regions beckoned his attention. One river—the Congo—was especially beguiling. He wondered how he could traverse that river and uncover its mysteries.
Then, it dawned upon Marlow that he could captain a steamboat on the Congo. This would give him the opportunity to satisfy his wanderlust and explore the majestic river. Immediately after, Marlow began to ask his male acquaintances about opportunities that would take him to the Congo region.
He came up empty there. However, his aunt promised to do everything she could to help him. Through her contacts, Marlow's aunt managed to get him an appointment as the skipper of a steamboat. Marlow was to work for a Belgian trading company with business concerns in the Congo region. By all accounts, the appointment came about quickly.
This was because the trading company had just lost one of its captains. Fresleven, a Danish man, had gotten into a quarrel with one of the natives regarding two black hens. Fancying himself double-crossed, Fresleven set about to deliver physical punishment to the man who had ostensibly wronged him. The man's son, coming across the scene of his father being abused, promptly threw a spear at Fresleven.
It was said that Fresleven died from his wounds. So, Fresleven's death and Marlow's aunt's intervention opened the way for Marlow to receive his appointment on board a steamship.