Lord Paddy Ashdown, one of Bosnia’s most active former High Representatives, died on Saturday evening at age 77 after a short illness.

“This is a hugely sad day for the Liberal Democrats and for the very many people across political and public life who had immense affection and respect for Paddy,” said Vince Cable, the current leader of the party in the United Kingdom.

Lord Ashdown served in the Royal Marines from 1959 until 1972 and later joined UK Foreign Office for four years. He was first elected to office in 1983. Five years later he was elected leader of the Liberal Democrats, a position he held until 1999.

He retired in 2001 and a year after he took over the post of Bosnia’s top international official to oversee the implementation of the Dayton Peace Agreement that ended the 1992-95 war.

Lord Ashdown had visited Bosnia and Kosovo during the wars there and was particularly interested in war crimes committed during those conflicts.

In 1998, he met with late Serbian President Slobodan Milosevic and handed over to him a letter from then-Prime Minister Tony Blair who was warning Milosevic to stop the operations of his army in Kosovo or risk being indicted for war crimes.

Lord Ashdown later testified against Milosevic at the U.N. war crimes tribunal in The Hague.

“I said that you would end up in this court and here you are,” he told Milosevic in the courtroom.

Lord Ashdown served in Bosnia from May 2002 until January 2006 and extensively used his power to annul or impose laws or fire local officials if they obstruct the peace agreement.

At the time, those were mostly Bosnian Serb officials. He remains disliked by politicians from the Bosnian Serb part of the country, Republika Srpska.

The Bosniaks, however, approved of his performance in the country.

Ever since it declared independence from former Yugoslavia, Bosnia had a friend in Lord Ashdown, the leader of the main Bosniak Party for Democratic Action (SDA), Bakir Izetbegovic, said.

“We will always remember his engagement as the High Representative when he played a pivotal role in important reforms in this country with his decisiveness, energy and political experience,” his statement said.

During Lord Ashdown’s mandate, Bosnia’s institutions have strengthened and its path toward Euro-Atlantic integrations have opened,” he said.

Izetbegovic said his party is also grateful for the Lord’s engagement after his mandate.

Lord Ashdown, along with two other former high representatives sent a letter to the EU last month, warning the Union of Croatia’s meddling in Bosnia’s affairs, which drew a series of condemnations from Zagreb.

”I am expressing my deepest gratitude for everything he has done for Bosnia and Herzegovina,” Izetbegovic said.

UK Ambassador to Bosnia, Matthew Field, wrote on his Twitter account that Lord Ashdown was a rite of passage for all new British Ambassadors to Bosnia.

“I found him insightful, challenging, generous, and deeply concerned about the country and its people. He inspired me. His passion and wisdom will be missed by many,” the Ambassador wrote.