Following the Invasion of Naboo in 32 BBY, Bail Organa joined the Republic Senate to represent his homeworld of Alderaan amidst the Separatist crisis and the Clone Wars where he was a strong advocate of peace and democracy. He was also the consort of Queen Breha Organa of Alderaan. In his time in the Senate, he formed ties with other progressive and peace minded senators like Padmé Amidala.
After the birth of twins Luke and Leia and the subsequent death of Padmé, Bail stepped up to adopt Leia, stating that he and his wife had always wanted a little girl. Bail, Obi-Wan Kenobi and Master Yoda decided it was best for the twins to be separated in order to keep them safe from their recently turned to the dark side father, Anakin Skywalker. Bail and Breha raised Leia peacefully on Alderaan for almost 20 years.
In 0 BBY, (Episode IV) Darth Vader and Governor Tarkin blew up the Organa’s home planet to cause Leia distress and make a point. Two billion people, including Bail and Breha, were killed in the blast.