Simplify the following text for a Grade 10 native English-speaking person.
Original: After serving in several party offices , he was appointed Minister of the Interior by Chancellor Willy Brandt , whose Social Democratic Party was in coalition with the FDP , in 1969 ; in 1974 , he became foreign minister and Vice Chancellor .
Simplified: From 1969 to 1974 , he was Federal Minister of the Interior under Chancellor Willy Brandt .