Original sentence: Popular Front of Estonia together with Popular Front of Latvia and the Sąjūdis organized Baltic Way through three Baltic states on August 23, 1989 that marked 50th anniversary of August 23, 1939 when Soviet Union and Nazi Germany signed Molotov-Ribbentrop Pact, which led to occupation  of these three states by Soviet Union
Edited sentence: Popular Front of Estonia together with Popular Front of Latvia and the Sąjūdis organized Baltic Way through three Baltic states on August 23, 1989 that marked 50th anniversary of August 23, 1939 when Soviet Union and Nazi Germany signed Molotov-Ribbentrop Pact, which led to occupation these three states by Soviet Union