John O'Sullivan's The President, the Pope and the Prime Minister sketches several elements of the leadership and activities of the three Western leaders during the late 1970s and into the 1980s when events began to coalesce. John Paul became a face for freedom's struggle by being selected as Pope of the Roman Catholic Church in 1978, Baroness Thatcher was elected Prime Minister in 1979 and President Reagan took office in 1980. O'Sullivan describes how each of the three initially came into leadership positions after some time on the sidelines, and focuses primarily on their interactions as they opposed the Soviet Union and Warsaw Pact nations. He offers some side information on how they interacted with each other, especially Reagan and Thatcher.
John Paul's role in strengthening Poles who insisted on religious freedom helped expose the economic weaknesses that had begun the erode Soviet power. Moscow did not have the resources to help Polish Communist leaders put down the freedom movements without overwhelming force, and the prospect of being frozen out of international trade left that option unusable. After O'Sullivan offers these details, he mostly switches to the role of Reagan, supported by Thatcher. PPPM reads quickly and offers substantial footnotes to look at more expansive treatments of the era's history and primary sources. Although the three did not necessarily coordinate their activities or even do the majority of their work at the same time, O'Sullivan's idea is that the three of them each took a swing at their Cold War opponents that eventually succeeded in breaking up both the Eastern bloc and the Soviet Union.
Adelman's eyewitness account of much of the negotiating sessions is the meat of Reagan at Reykjavik: Forty-Eight Hours that Ended the Cold War. He also describes some of the lead-up to the summit and its context -- news organizations following Raisa Gorbachev around the city because they'd brought immense teams to cover an event that was going on behind closed doors, for example.
According to the way Adelman saw it, one thing that media coverage got both right and wrong was the role of the Strategic Defense Initiative (SDI) space-based missile shield. This plan, usually referred to "Star Wars" because of its near science-fictional operating system of lasers shooting at rockets, was something Reagan believed in passionately because of his hatred of the threat of nuclear annihilation. Adelman notes that Reagan believed in SDI more than some of its planners, possibly being overly optimistic about the timetable for its effective completion. His commitment to it would not allow him to agree to test it only in the laboratory instead of in the field. Whether Gorbachev believed SDI would work or not, he knew that Reagan did and he remained firm.
But faced with increasing economic troubles at home, the USSR eventually had to turn resources from military use to other areas, and the 1987 INF treaty conceded the point. Adelman may overstate his case; whatever major role Reykjavik played in the collapse of Soviet power was not the only factor. Much subsequent writing on the end years of the Cold War downplays Reagan's work and sometimes even Gorbachev's, focusing on economic tides that neither man would have had much success in turning or reinforcing. But it's difficult to imagine stolid party oldtimers like Konstantin Chernenko or Yuri Andropov "smelling the coffee" of economic reality the way Gorbachev did, and Gorbachev himself said that the negotiations and treaties would probably not have happened had he been across the table from anyone but Reagan.
The Cold War ended either way, and whether it happened because stalwart defenders of freedom led three major opponents of Soviet power or because economic inevitability picked that decade to come due or because of a mixture of both views, it's interesting to revisit events I can remember and judge how I see them after a few more years turning calendar pages. Both books are worth the time and can offer material worth thinking about.