The manse population would surpass the island's population but they fear for exposure in going open (not to mention moral question) in kidnapping entire population. So they made deal with island god/goddess to demand to 'drown' victims or else catastrophe will occur (they faked storm or rising tide with sorcery), so in return for more obedient island villagers (and additional prayers from manse) the god/goddess helps guide the drowned sacrifice victims to the first age submarines (and protect sacrificed young men/women from sea life like sharks and other things).<br/><br/>Also said god/goddess another angle could had been bribed by sidereal to perform demand for sacrifices (instead just throwing people through the portal which is used for bringing in more individual cases). But I sort imagine it's funnier if simply military crew wearing full first age regalia of submarine corps just walks on beach and local natives start 'worship' them as sea demons or such and so they used some language charms (the DB's) formed contact and formed established false religion.<br/><br/>So in theory island folks could provide at max cult 1 or 2 dot background to soldiers who regularly 'participate' in walking on beach and taking sacrificial young men and women with them underneath the ocean. Exploiting the superstition.