(FORTUNE Magazine) – HE WAS NOT LOOKING for this kind of ''defining moment'' to mark his presidency. But now that war has arrived, future historians are sure to agree on one thing: The world's response to the conflict sparked by Saddam Hussein's brutal conquest of Kuwait bears the stamp of one man -- George Herbert Walker Bush. From the beginning, Bush considered Saddam's unexpected invasion a threat akin to Adolf Hitler's annexation of the Czech Sudetenland in 1938. ''Blitzkrieg'' was the word the President chose to describe it. Says younger brother William ''Bucky'' Bush: ''He was convinced that Saddam has the same sort of objectives and character as Hitler, the same willingness to use blatant aggression and to brutalize a country.'' Those parallels were reinforced by a book Bush was reading when Saddam first attacked, Martin Gilbert's The Second World War: A Complete History. Bush also had direct experience with World War II, in which, at age 18, he became the Navy's youngest fighter pilot. That, too, shaped his response. Says Wyoming Senator Alan Simpson, an old friend: ''He remembers that people said Hitler was just a benevolent dictator. He doesn't want to repeat history. He's thinking of his grandkids, of the future.'' Unchecked, Bush believed, Saddam would take over Saudi Arabia and hold oil- dependent Western economies hostage. Even more troublesome, a victorious Saddam could finance the ''holy war'' he had often called for against moderate Arab states, Israel, and the West. Aware that his Administration had bungled by not giving a clear enough signal about how America would respond before Saddam struck on August 2, Bush moved quickly to correct that error. Containment was not enough, he declared three days after the invasion: ''This will not stand.'' Bush then used his first address to the nation to lay out his goals: to defend Saudi Arabia, to get Iraq out of Kuwait unconditionally and restore its legitimate government, to secure the release of Western hostages, and to ensure the security and stability of the Persian Gulf. Some of his advisers believed this last goal required nothing less than the elimination of Saddam Hussein, his military machine, and his weapons of mass destruction. White House officials insist Iraq was within months of developing a crude nuclear device. Says Utah's Orrin Hatch, ranking Republican on the Senate Intelligence Committee: ''Removing Saddam and neutralizing those threats has been on Bush's mind since the beginning.'' In foreign affairs, Bush correctly understood, you can't just bluff. While he publicly described the sending of troops to Saudi Arabia as ''wholly defensive,'' he was prepared to go further if necessary. Says a close friend: ''Bush hoped that economic sanctions plus military threat would work. But all along he thought they might not.'' As early as August 5, at a meeting in Camp David -- down the hall from a bullet-ridden image of Bush that Panamanian dictator Manuel Noriega had used for target practice -- Chairman of the Joint Chiefs of Staff Colin Powell had convinced him that if force were to be used, it should be quick and massive. In the early months of the trade blockade, Bush and his aides worried that the 230,000 U.S. troops they had initially deployed were vulnerable to Iraqi attack. ''At some point, one of our planes could accidentally get shot down, and we'd have to go to war,'' the President confided to a top aide. By October, Powell was pushing for a major increase in the U.S. military presence. Even before the midterm elections on November 6, Bush decided to nearly double America's troop strength. But to avoid making it a campaign issue, the former Republican Party chairman delayed his announcement until November 8. Critics who warned that Bush had set the clock ticking on Saddam's withdrawal from Kuwait were correctly stating what the President had in mind. The longer the world waited, the more Saddam's army would become entrenched, the more atrocities Kuwaitis would suffer, the longer oil prices would stay up * -- damaging Western and Third World countries -- and the greater the risk the U.N. coalition would crack.

Throughout the buildup to conflict, Bush proved wise in using the U.N. to keep the world moving together toward a resolution of the crisis. Minutes after national security adviser Brent Scowcroft told him of the invasion, Bush phoned U.N. Ambassador Thomas Pickering, instructing him to call for a session of the Security Council to condemn Saddam's action. Over the next four months, the Security Council passed 12 resolutions, each tightening the vise on Iraq. The last and most decisive one, passed in late November, set the deadline authorizing the use of force. To win, build, and maintain his coalition, Bush, as well equipped as any modern President has been to play his own chief diplomat, kept up a barrage of personal phone calls and visits to world leaders. With the Cold War behind him, he felt strongly that this was the time to shape a ''new world order.'' America would join with the Soviet Union and other nations to oppose ''naked aggression'' and replace the old superpower spheres of influence with respect for international law. But he was practical enough to know that a little logrolling makes idealism easier to swallow. So the U.S. forgave $7.1 billion in military loans to Egypt, granted textile trade concessions to Turkey, and lifted political sanctions imposed on China after the Tiananmen Square massacre, among other moves. The President and his men worked overtime to quash freelance peacemakers in the Arab world, France, and the Soviet Union who threatened to give Saddam a face-saving way out of the box Bush was building. Over and over, Bush repeated the mantra: no negotiations, no deals, no face-saving, no rewards, and specifically, no linkage to a Palestinian peace conference. As the U.N. deadline approached, the President grappled one last time with the morality of going to war. At the Christmas holidays, he pored over every one of the 82 pages of Amnesty International's agonizing report of arrests, rape, and torture in Kuwait. In the first staff meeting after his 12-day respite at Camp David, he told them his conscience was clear. Recalls one who was there: ''He said, 'It's black and white, good vs. evil. The man has to be stopped.''' By that point Bush had already begun writing the speech he would deliver on the night Operation Desert Shield exploded into Desert Storm. In the end game leading up to January 15, Bush's adversary gave him some critical help with his domestic diplomacy -- the area where Bush's performance had been weakest. Before the Geneva meeting between Secretary of State James Baker and Iraqi Foreign Minister Tariq Aziz, the White House was uncertain whether Congress would give its formal assent to the use of force. But after Aziz left Bush's letter to Saddam sitting in the middle of the conference table like some used napkin, the way was cleared for an essential congressional endorsement. During his career, Bush has time and again proved himself skilled in the art, essential to diplomats and card players, of concealing his hand. And so he did with the launch of Desert Storm. Until shortly before the official announcement at 7:06 P.M. E.S.T. January 16, only a half dozen top aides knew of the President's decision. To avoid tipping off Saddam, Bush delayed calling members of the U.N. coalition until an hour or two before the invasion. Instead of inviting congressional leaders to a White House staked out by reporters, he dispatched deputy national security adviser Robert Gates to the Hill for private briefings. As the bombs began bursting over Baghdad, he summoned press secretary Marlin Fitzwater to the Oval Office. ''Go do it,'' he ordered. Minutes later, Fitzwater read a statement by the President to a packed White House briefing room: ''The liberation of Kuwait has begun.'' That was a conscious reminder of Dwight Eisenhower's D-Day announcement of ''the liberation of Europe,'' the last great war against aggression won by America and its allies. HAVING MADE his decision, Bush did not look back or engage in unnecessary micromanagement in the crucial early hours of the conflict. Unlike Jimmy Carter during the failed 1980 mission to rescue American hostages in Iran, he made no calls to field commanders. Instead, he got his information through Scowcroft and regular written updates from the situation room, the military nerve center in the White House basement. He even went to bed on January 16 at his regular 11 P.M. What's at stake in Bush's fateful decision cannot be overstated. If the initial military successes prove ephemeral, the casualties mount, and the conflict drags on, Bush will go the way of L.B.J. The world's economic woes will deepen. America's leadership role in the world will suffer lasting damage. And 1992 could well see a Democrat win the White House. But if the war is short and successful, George Bush will emerge a hero, the man who united the world to repel aggression. The global economy will get a welcome lift of confidence. And America's 41st President could almost certainly count on six more years to build his fragile new world order into something more permanent.