Sentence 1: Following the invasion of Poland by Nazi - Germany and the Soviet Union in 1939 , Osterwa became active in underground education , but was also sick .
Sentence 2: After the invasion of Poland by Nazi - Germany and the Soviet Union in 1939 , Osterwa was active in underground education , but also became ill .
Question: Do Sentence 1 and Sentence 2 express the same meaning? Yes or No?