Simplify the following text for a Grade 14 native English-speaking person.
Original: Later in June , Amedeo , Duke of Aosta , the Governor-General and Viceroy of Italian East Africa , convinced the Italian Supreme Command ( Comando Supremo ) to plan a campaign to conquer British Somaliland .
Simplified: In June 1940 Amedeo , Duke of Aosta , the Governor-General of Italian East Africa , convinced the Italian Supreme Command ( Commando Supremo ) to plan a campaign to conquer a British colony : British Somaliland .