Dole, R-Kan., and Inouye, D-Hawaii, first met at a military hospital as they recovered from wounds sustained during World War II.
Inouye, the second-longest-serving U.S. senator in history and a Medal of Honor recipient, died Monday at age 88. His casket was carried from the Capitol to the National Cathedral in Washington Friday by an eight-member U.S. military honor guard.
Inouye's relationship with Dole is storied.
After meeting in a Michigan Army hospital the two then served in Congress for nearly 30 years, Roll Call reported Thursday.
Dole eventually served as the Senate's top Republican, and then left Congress for a presidential run. Inouye remained in the Senate, becoming president pro tempore and chairman of the Appropriations Committee.
Dole, who used a wheelchair when he visited his former colleagues this month to urge their support of a U.N. disability rights treaty, didn't attend a Thursday morning service at the Rotunda, but arrived in the late afternoon as part of a cycle of visitors paying their respects to Inouye.
He walked to the casket Thursday, accompanied by his wife, former Sen. Elizabeth Dole, R-N.C.
Roll Call said the Doles stepped onto the small platform of the catafalque on which the casket rested so they could put their hands against the flag.
Overcome with emotion, Dole shook and wiped away a tear.
He could have used his wheelchair but chose walk, he told Roll Call, because "I wouldn't want Danny to see me in a wheelchair."
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