Joe Cahill, 84, a founding father of the modern Irish Republican Army who once narrowly avoided the hangman's noose, died July 23 at his home in Belfast. He had asbestosis, a lung-ravaging condition he acquired while working in Belfast's Harland and Wolff shipyards in the 1950s.

Mr. Cahill was the first Belfast commander of the modern Provisional wing of the IRA, founded in December 1969, the year Northern Ireland descended into decades of civil unrest.

He was also the principal mentor of Sinn Fein leader Gerry Adams, who, as an IRA member, served under Mr. Cahill's direct command in the early 1970s, when the IRA began killing British soldiers and police and bombing towns and cities in Northern Ireland and England.

After killing about 1,800 people and maiming thousands, IRA commanders called open-ended cease-fires in 1994 and 1997 -- when Mr. Cahill's vote in favor was considered critical.

Mr. Cahill, a Belfast native, was sentenced to death alongside five other IRA members for killing a policeman in 1942. While one of his colleagues, Tom Williams, was hanged, Mr. Cahill and the others had their sentences commuted to life. British authorities freed him in 1949.

Mr. Cahill remained in the old IRA through a 1956 to 1962 campaign, but, like many northern hard-liners, he broke from the Dublin-based organization when it failed to defend Catholic parts of Belfast adequately from Protestant mob violence in August 1969.

Mr. Cahill quickly rose through the ranks of the fledgling Provos, as the new IRA wing was nicknamed. He also traveled to the United States to help found Irish Northern Aid, the Provisional IRA's fundraising arm overseas.

In 1972, he became IRA chief of staff, the senior day-to-day command position, and moved to Dublin to avoid capture by British security forces.

He pioneered contacts with Libyan dictator Moammar Gaddafi and, in March 1973, was caught by the Irish navy as he tried to smuggle five tons of Russian-made explosives, rifles, pistols and ammunition from Libya.

After being freed from prison in 1975, Mr. Cahill rejoined the IRA's seven-member command alongside Adams and Martin McGuinness, another new-generation IRA commander from Northern Ireland's second-largest city, Londonderry. He oversaw renewed contacts with Libya that led to four massive weapons shipments in the mid-1980s, much of which remains in secret IRA depots today.

Under the Adams-McGuinness leadership, the IRA modernized its practices and sought to develop Sinn Fein, its largely irrelevant political wing, into a substantial political party that began contesting elections in Northern Ireland in 1982 and the Republic of Ireland in 1987.

Mr. Cahill supported the move and became Sinn Fein's treasurer, responsible for funneling money from U.S. supporters to Sinn Fein and the IRA. He was deported from the United States after entering illegally in 1984.

Underscoring Mr. Cahill's influence within IRA circles internationally, President Bill Clinton gave Mr. Cahill an exceptional visa waiver to travel to the United States to reassure U.S. supporters immediately before and after the 1994 cease-fire declaration.

Mr. Cahill spoke out strongly in favor of accepting the Good Friday peace accord of 1998, which offered a chance for Sinn Fein to help govern Northern Ireland, a state the IRA long hoped to abolish rather than reform.

But to his dying day, Mr. Cahill insisted that shifting Sinn Fein-IRA tactics would ultimately deliver the goal of uniting Ireland under one government, a goal that Northern Ireland's Protestant majority opposes.

Survivors include his wife, Annie, and seven children.

Joe Cahill devoted his life to achieving a united Ireland. The Provisional Irish Republican Army wing, which he helped lead, formed in 1969.