"We have lost a great President, a great American and a great man," Thatcher said in a recorded eulogy played Friday at the U.S. National Cathedral in Washington, D.C.
"His politics had a freshness and optimism that won converts from every class and every nations," Thatcher said. "He won the cold war not only without firing a shot, but also by inviting enemies out of their fortress and turning them into friends."
Thatcher and Reagan shared similar conservative philosophies and worked closely during the last decade of the Cold War, which ended just after Reagan left office.
Thatcher's was the first of four eulogies to be delivered at Reagan's funeral. She preceded former Canadian Prime Minister Brian Mulroney, Former President George H.W. Bush and current President George W. Bush.
Notable deaths of 2014 [PHOTOS]