“George W. Bush depends on Laura for friendship, calmness, security and sustenance, and that private dynamic is so much more important than what she does publicly,” historian Doris Kearns Goodwin tells PEOPLE in its latest cover story, on the First Family’s first year in office. “Only those who know them up close understand how he draws strength from her,” says Goodwin, an acquaintance of the Bushes. Adds Kati Marton, author of “Hidden Power: Presidential Marriages That Shaped Our Recent History”: “No man needs a partner more than a president in a time of crisis. And for George Bush, Laura is his rock.” Just a year ago, when her husband took office after the most controversial election in U.S. history, the First Lady, 55, was looking forward to keeping a comfortably low profile. But virtually from the moment the first hijacked plane crashed into the World Trade Center on Sept. 11, the former school librarian and teacher, homemaker and devoted mother faced a historic task: Comforting a nation that has suffered its most lethal and emotionally devastating attack ever, as well as preside over the White House during a worldwide war on terrorism that threatens to last for years. And in the midst of it all, she must provide a source of strength to the man at the helm.