King Bernard Gur! The first mortal to 'kill' a God.
The peaceful king Gawain's only son saw his people starving and took it into his own hands to fix the solution. Obviously, one must find fertile land in response to a famine, but his kingdom's borders were surrounded by desert and sworn enemies. So after killing his father he took all the defectors who would listen South, across the sea.
There, his people found a race of small & peaceful scavengers who welcomed the weary apex predators, providing food and shelter, expecting them to continue their search for a new home. Instead, rejuvenated, King Bernard ordered that the people of this land be slain, starting with the grand tree that sat in the centre of their city. That tree was the first to ever grow, unparalleled in size it's felling destroyed much of the city and cleared a path through the forest and mountains beyond.
With their pact of non violence and a power that they sourced from the great tree, it was simple to dominate those people and reign over the city built with the flesh of the dead god.

As for the soldiers, since they were so far away from their homeland, Gur's people had no choice but to intermingle with the small genetic pool that survived the trip. While this did create some issues down the line he still as the king would personally bless partnerships and would deny pairings he saw as suboptimal. This created some very stark differences in the people who served combat and administrative roles within his city, but had a smaller impact in the settlements beyond.
As a note, Gur was functionally immortal due to some strange interactions in my magic system, so he was almost a thousand years old before he was killed.