Laura Roslin serves as Secretary of Education at the time of the Cylon attack, later becoming President of the Twelve Colonies, despite never actually being elected to office.

Some time before the Cylon attack on the Twelve Colonies, Roslin's father and sisters (one of whom was pregnant) were killed in a car accident at the fault of a drunk driver (Daybreak, Part I).
Roslin, an unmarried[1] former teacher, worked with Richard Adar when he was a mayor. Over the twenty years in politics, she herself has risen in political rank to the office of Secretary of Education.
Adar, a married man, and Roslin are in a sexual affair[2] during the events of a teachers strike that she is trying to mediate, to Adar's objection.
Roslin learns that she has breast cancer - as did her mother. Unfortunately, the diagnosis is grim, as the cancer has already spread.
Roslin sat in the Government Plaza after her doctor's appointment, where she saw Gaius Baltar, the famous scientist, walking and kissing an attractive blonde, but pays it little attention.
Roslin successfully resolves the teachers strike crisis, but Adar vehemently disagrees with her method, and asks for her resignation. She asks him to defer the matter until she returns from the decommissioning ceremonies on battlestar Galactica.
Despite being thrust into the role of President in highly unusual and stressful circumstances, Laura Roslin initially proves herself both tough and capable within the role. Initially in awe of Commander Adama, and worrying that he didn't hold her in high regard (Water), she quickly overcomes her doubts and fears to be able to make the required decisions at the right time, and also stand up to Adama himself (You Can't Go Home Again). She is always prepared to put the safety and destiny of the Fleet first, no matter what the cost of her actions ("Flesh and Bone", "Home, Part I", "Home, Part II", "Lay Down Your Burdens, Part II") while remembering her limitations and fears.
Roslin is rarely hesitant to make controversial decisions unilaterally, but often must deal with the significant ramifications of her choices.