Hello. You did not post the announcements that the question refers to, but I can help you, since the announcements that reflected European views at the time of imperialism, generally displayed obvious ideas about the purity and superiority of the white man and the idea that colonies are dirty places without civilization.
The idea of purity and superiority is related to the idea of the "white man's burden", which was a concept that stated that it was a duty (given by God) to Europeans to "clean up", take Christianity and dominate regions with inferior people , in this case, non-white people who lived in other countries, who were considered unclean and therefore needed to be purified by whites.
In this way, Europeans used a strong racist bias to dominate and enslave peoples of other ethnicities, promoting imperialism while claiming that this was the role that God had assigned to whites in this world.
In England, the doctrine that allowed the courts to hold protective jurisdiction over all children was called parents patriae.
