Simplify the following text for a Grade 10 native English-speaking person.
Original: Directly following the establishment of the Geneva Convention , the first national societies were founded in Belgium , Denmark , France , Oldenburg , Prussia , Spain , and WÃ 1\/4 rttemberg .
Simplified: The first national societies were founded in Belgium , Denmark , France , Oldenburg , Prussia , Spain , and WÃ 1\/4 rttemberg .