George HW Bush's presidency left the world a more peaceful and stable place

• There is a convincing case to be made that George H.W. Bush was one of the greatest global leaders of all our presidents, writes Nicholas Burns, former U.S. ambassador to NATO.
• No other president came to the White House better prepared to lead internationally.
• Bush's steady, civil bearing came through at the most challenging moments, including the fall of the Berlin Wall and the collapse of the Soviet Union.

Jonathan Utz | AFP | Getty Images

Soviet leader Mikhail Gorbachev (L) and US President George H.W. Bush (R) shake hands on December 2, 1989, aboard the Soviet cruise ship Maxim Gorki before the start of their first summit meeting, just a few weeks after the fall of the Berlin Wall. The summit is viewed as the official end of the Cold War. 

Where does the late George H.W. Bush rank in the history of the American presidency? Historical judgments are best left to historians who can appraise a president most accurately, often decades after his death.

There is a convincing case to be made, however, that Bush was one of the greatest global leaders of all our presidents.

I admit to a bias, as I worked for him as an advisor on Soviet affairs at the White House's National Security Council for the last 2½ years of his presidency. Yet his achievements on the world stage were the most important of any president during the last half century. In just one term in office, from 1989 to 1993, he was the indispensable leader in ending the Cold War peacefully as the Soviet Union collapsed and 15 new states took its place in December 1991. Bush was the major figure in unifying Germany in the NATO alliance following the fall of the Berlin Wall.

He also organized an extraordinary global coalition to defeat Saddam Hussein in the 1990-91 Gulf War. He then presided over the creation of the modern Middle East peace negotiations between Israel and the Palestinians later that year. And we shouldn't forget that his administration conceived of the North American Free Trade Agreement and handed it over to President Bill Clinton, who secured congressional approval early in his presidency.

On their own, each of these achievements would be considered consequential for any president. Together, they represent an extraordinary collection of successes that made America and the world more stable and peaceful.

It wasn't a given, however, that the Cold War would end peacefully. In fact, we worried inside the U.S. government about all sorts of crises that might unfold as the Soviet Union neared its eventual collapse on Christmas Day 1991. A cabal of KGB and Red Army leaders actually overthrew Soviet leader Mikhail Gorbachev for two suspenseful days in August of that year.

We worried there might be another challenge to Gorbachev and Russian Republic President Boris Yeltsin again that autumn which could provoke conflict inside the country or seek to obstruct the freedom of the USSR's former satellites in Eastern Europe. We were also acutely concerned that the USSR's vast collection of nuclear weapons and nuclear material might fall into the hands of a breakaway warlord across that vast country or into the hands of a criminal network.

Bush's singular achievement was in creating a relationship of trust with both Gorbachev and Yeltsin. That reassured them the U.S. would not seek to take advantage in the Cold War's last months.

It was also not a given that West and East Germany would unify peacefully as communism collapsed after the fall of the Berlin Wall in November 1989. British Prime Minister Margaret Thatcher and French President Francois Mitterrand, both with clear memories of the Second World War, were initially skeptical as they pondered the reappearance of a powerful German state in the center of Europe. Some German leaders advocated a reunited neutral Germany between Russia and the West.

Bush knew both of those scenarios would be destabilizing. He was looking to the future and so he swung his support behind German Chancellor Helmut Kohl's aim for a united German nation — but one embedded in the NATO alliance.

It was also not a given that a U.S.-led coalition would be able to defeat Saddam Hussein's army without major U.S. and allied casualties. Bush worked the phone for months to persuade an unprecedented collection of Arab, European, Asian and North American countries to pull together over 700,000 allied forces under U.S. and Saudi leadership. Saddam was driven from Kuwait and defeated with a surprisingly low level of allied casualties.

Bush and his supremely capable secretary of State, James A. Baker III, also launched what they called "Operation Tin Cup" to persuade the world's wealthiest countries – among them Japan, Germany and Saudi Arabia – to pay for the entire war effort. The blessing of the United Nations Security Council gave the Gulf War global credibility.

Why was Bush such a successful leader in foreign affairs? He had a combination of unrivaled international experience and skill in building close and trusting relations with other world leaders.

No other president came to the White House better prepared to lead internationally. Bush knew politics from his time as a member of Congress and chairman of the Republican National Committee. He had worked as a front-line diplomat as ambassador to the United Nations and minister to China just after Nixon's opening of relations with Mao.

He understood the military from his World War II combat service as a naval aviator and his eight years as vice president. And he knew the intelligence world due to his service as director of the CIA.

Bush had an especially intimate feel for diplomacy. By the time he became president, he had the world's most extensive collection of relationships with presidents, prime ministers, monarchs and business leaders. He understood that effective diplomacy required the patient building of trust, something that often eludes leaders across national, ideological and cultural boundaries in our era. This was an essential factor in nearly all his many foreign policy successes as president.

Bush's combination of in-depth knowledge and sophistication about the world, along with his ability to connect to other leaders personally, was the key to his approach to the presidency.

One of the reasons Bush was so widely admired by those of us in the career foreign service and by our colleagues in the military was that he believed in us. He believed in the power of government to do great things. And he also governed by seeking to unite us as Americans, not to divide us.

There is no doubt, however, that there was something else about him that made people like and trust him and want to follow his lead — his humility. This is apparent in an excerpt of a conversation with his granddaughter Jenna that has been circulating on social media in the days following his death. "I think history will point out some of the things I did wrong," he told her, "and maybe even some of the things we did right." In other words, he was the all-too-rare leader who took responsibility for defeats and shared the credit with others when things went well.

It was that aspect of George H.W. Bush's character that made all of us who worked in his administration admire him. He delegated to members of his Cabinet, including Baker and Secretary of Defense Dick Cheney. He gave the credit to other leaders. He assembled what many believe was the most effective national security team since the late 1940s: Baker, Cheney, Treasury Secretary Nick Brady, Bush's close friend and extraordinarily effective National Security Advisor Brent Scowcroft, Chairman of the Joint Chiefs Gen. Colin Powell, Bob Gates, Condi Rice, Bob Blackwill, Bob Zoellick, Bob Kimmitt, Dennis Ross, Tom Pickering and Ed Hewett.

Roland Witschel | picture alliance | Getty Images

(L-R): Mayor of Berlin Richard von Weizsaecker, US Vice President George H. W. Bush and German Chancellor Helmut Kohl visit the Berlin Wall, on Jan. 31,  1983. 

Bush's steady, civil bearing came through at the most challenging moments. When the Berlin Wall was opened to two-way East-West traffic in November 1989, his staff, many members of Congress and half the press corps urged him to go to Berlin to proclaim the end of communism. Bush's reply was: "I'm not going to dance on the wall." While there is no question that he would benefited politically at home by "dancing on the wall," Bush saw it was more valuable to avoid humiliating Gorbachev as he would surely need his trust for the even bigger challenges while communism unraveled across Eastern Europe.

This rare quality of leadership — of putting the national interest before his personal interest — persisted throughout his presidency. When it was clear that the USSR would finally collapse in December 1991, many of us on the White House staff urged the president to give a major speech to the nation on our victory in the Cold War. The president resisted for weeks. Then, on Christmas Eve 1991, Scowcroft called Hewett and me to say the president had relented. He would give the speech after all and a draft was needed at 8 a.m. Christmas morning!

Bush addressed the American people Christmas evening. Typically, he did not proclaim it as a victory for what he had done but what we — America and our allies — had achieved.

"Every American can take pride in this victory, from the millions of men and women who have served our country in uniform, to millions of Americans who supported their country and a strong defense under nine presidents," he said.

Bush went on to pay tribute to Gorbachev, whom he had called a few hours earlier to say good-bye. He spoke for the entire nation when he looked into the future toward "a new world of hope and possibilities and hope for our children, a world we could not have contemplated a few years ago."

Perhaps that was George H.W. Bush's greatest gift to America — his boundless grace, dignity, integrity and his everlasting hope for America and the world. Looking back, we were fortunate indeed that he was the president in the Oval Office when he helped the world change, for the better, at the Cold War's end.

Nicholas Burns, a CNBC contributor, is the Roy and Barbara Goodman Family professor of the Practice of Diplomacy and International Relations at the Harvard Kennedy School of Government. He served in the United States government for 27 years, including as under secretary of State for political affairs and as the U.S. ambassador to both NATO and Greece. He also served as director for Soviet Affairs in the administration of President George H.W. Bush.