Haunted by too many battles, his participation in the First World War is as a medic, rather than as a soldier, helping Sean Burns, who is by now a doctor treating the wounded, ("Deliverance"). He is caught in a gas attack launched by Xavier St.Cloud, ("For Tomorrow We Die"), but they are disturbed before Xavier can take his head. On the last day of the war, he sees Simon Killian order an attack after the war is over and subsequently testifies at Killian's court martial, ("The Colonel"). He begins to travel, but is followed by revolution, first to Russia, where he persuades Artur Drakov to spare his employer's life, ("Warmonger"), by agreeing never to challenge Drakov, then to Ireland, where he turns down Annie Devlin's plea to help the Republican movement, ("Eye For An Eye"). He returns to Paris, where he meets an old enemy. He fights Kalas, but the fight ends when Kalas' throat is slit, destroying his voice, ("Methos"). As the year closes, he returns to America, where he is witness to a strike at a Pennsylvania mining company, which leads to the shooting of the miners and the mine owner's son by company guards, ("The Zone").

From now on, MacLeod's life becomes increasingly fragmented, as he begins to abandon his journalist identity in favour of a life as an antiques dealer, (perhaps influenced by Connor). He couples this with an involvement with British Intelligence, which increasingly takes him against the Nazis. He spends the 20s in America, mostly in the Pacific North West, with Michael Moore in 1921, ("Turnabout"), and in 1925 when he takes Marcus Korolus' head, ("See No Evil"), but he does visit Boston, ("Bless The Child") at least once, in late 1923, and he spends an extended period in 1926 in the South, where he meets Carl Robinson, ("Run For Your Life") and Amanda, ("Money No Object"), during her Bonnie and Clyde series of bank raids with Cory Raines. After telling new Immortal Johnny Kelly what he is and being rejected as his teacher, ("Glory Days"), he returns to Europe. He visits Hugh Fitzcairn on the occasion of his funeral and helps the for-once prosperous Fitz sift through some very Unusual Suspects to find his would-be murderer. He leaves his friend to return to Paris, where he meets Tarsis and his student, Lucas Kagan, and takes Tarsis' head, ("Reasonable Doubt"). In Berlin in 1935, on behalf of British Intelligence, he works with Ingrid Henning to recruit anti-Nazi Germans, ("The Valkyrie"), but the next year he again bumps into Amanda, ("The Return Of Amanda", curiously enough), after which he makes his way to Spain, covering the Spanish Civil War as a journalist. Here, he first encounters John Kage, ("Blind Faith"). Unable to stand by as Europe begins to disintegrate, he tries to help refugees to escape Stalinist Russia with the aid of Alexei Voshin, ("The Sea Witch"), but Voshin betrays them and the refugees are killed. His final trip to Seacouver is as an antiques dealer, where he meets Benny Carbassa and is killed by gangster Sid Lankovski, ("Vendetta"). As the year ends, he meets and falls in love with a mortal, Linda Plager, ("Studies In Light"), but when she leaves him, there is nothing to keep him in Seacouver.

It is unclear what MacLeod did in the early days of the war, although he was in London during "The Blitz" of 1940. By 1943, he was in Paris, working undercover with the French Resistance, where he encountered Ernest Daimler, ("Mortal Sins"), but left for Marseilles before they could face each other. In 1944, he helps Ingrid Henning in the unsuccessful plot to assassinate Hitler in his Bavarian stronghold.

After refusing to help terrorist Liam O'Rourke in his murderous activities, he was instrumental in seeing O'Rourke jailed for his crimes, ("To Be"). He was still in England in the winter of 1950, when a game of golf with Amanda and Hugh Fitzcairn led to the unlikely trio breaking into Westminster Abbey to steal "The Stone of Scone". He later returned to the US, where he met up with Carl Robinson in the still segregated South, ("Run For Your Life"). In 1958, hunting Bryce Korland in Greenwich Village, he met Kol T'ek again, by now known as Jim Coltec, ("Something Wicked").

The sixties are unchronicled at present, but MacLeod was in Cambodia in 1975, helping refugees escape, when he met Kage again. He returns to France, living the playboy lifestyle at the Casino Montecour in 1978, ("The Ransom Of Richard Redstone"). In 1980, he was hunting Kuyler in Paris when he was forced to flee from the police, who were also hunting the assassin. To elude their pursuit, he jumped onto a tourist boat on the Seine and straight into an argument with the guide, a young art student called Tessa Noel. In 1983, he told Tessa what he was, ("Counterfeit") and, after she accepted what that meant, they set up an antiques store in Seacouver. This was a period of calm for MacLeod, away from wars and The Game, although he nearly settled his feud with Walter Reinhardt on New Year's Eve 1988. His peace was largely undisturbed until 1992, when Slan Quince challenged him, ("The Gathering").