Casca 2: God of Death refers to Casca meeting Machiavelli.  Casca 20: Soldier of Gideon mentions Casca seeking the new Protestant religions in Switzerland and Germany, while Casca 21: Trench Soldier has a reference to Casca fighting in the army of Charles V.

Casca returns to Europe and joins the army of the Spanish King Charles V, who is also Emperor of the Holy Roman Empire.  Charles campaigns in Italy and Casca is part of the victorious campaign.  He also meets Machiavelli, in his twilight years.  Victory at Pavia is followed by the infamous Sack of Rome (1527) and Casca quits, disgusted at the conduct of the army.  Hearing of new religions rising in Switzerland and Germany, Casca goes to meet those preaching, hoping it is Jesus returned, but finds that Zwingli and Luther are merely men with new religious ideals.

He does join Luther's Saxon followers in a rising and fights in Thuringia.  When he hears of another new religious leader in England, Casca quits his commission and crosses to find the King, Henry VIII, is the man behind it, and again not Jesus.  Captured and tortured by the Brotherhood, Casca is eventually released when Henry's army sacks the monastic order the Brotherhood is disguised as.

He returns to the Continent and rejoins the conflict there but is defeated at Muhlberg in 1547 and the survivors, Casca included, are chased well into Germany.  Casca heads east away from the religious disorder.  Here, he is confronted by two unruly Cossacks and Cacsa kills both with his bare hands that impresses the other Cossacks, and Casca in accepted into their community.

War looms and the Cossacks and Casca joins Ivan's army in the conflict against Poland and Sweden, but then news reaches them that the Tsar's army has turned on their village and destroyed it.  After returning to bury the dead, Casca bids a sad farewell and travels west and eventually arrives in Spain.

He gets into an argument with arrogant Spanish troops which ends with 3 dead and 4 wounded and Casca a captive.  Sentenced as a slave to the galleys, Casca partakes unwillingly in the Armada to England, and his ship is wrecked and ends up on the beaches of eastern England.  Casca is the only survivor and makes it to a small village where he settles down as a fisherman.  

Casca 21: The Trench Soldier mentions Casca fighting in the Thirty Years War.

Living with the villagers for a while, Casca moves in with a widow, and things are settled until more religious discord sweeps the country.  Branded a witch, Casca barely escapes with the mob after him, and he sails across the sea to Sweden where the country is about to go to war with Denmark.  Riding to sergeant, Casca impresses the new king Gustav Adolph, and is promoted to Count of Hapsal, one of the newly conquered regions following wars with Norway and Russia.  He administers land there until the Thirty Years War breaks out and Casca goes with the King and the army to Germany to fight.

At Breitenfeld (1631) the Swedes triumph but a year later at Lutzen the King is killed, although Casca and the other officers rally the Swedes to victory.  But then in 1634 at Nordlingen the Swedes are badly beaten and Casca is left for dead on the battlefield.  When he recovers, he makes his way to the reforming Swedish army and rejoins, this time as a private, and fights until the end of the war.

He moves east and finds another Cossack people, the Zarapog, who are being oppressed by the Poles.  Seeing an opportunity to help them, Casca joins them and fights in the revolt.

After the revolt is over, he moves south west as war with an old enemy is coming, and he joins the Austrians in Vienna just before the Turks arrive to beseige it.  Evenutally the Austrians, helped by the Poles, triumph, and Casca is part of Prince Eugene's army that liberates Hungary from the Turks.  Rising to Captain, Casca campaigns successfully in Transylvania.  But when the war finishes, Casca decides to head for a new conflict, where Spain and France are facing a coalition of allied powers.

Casca joins the Allied forces as a British grenadier under John Churchill and the campaigns during the way sees many battles, such as Blenheim and Malplaquet.  Casca's experience helps him through the bloody war and at the end of it is shipped back to London where he's billeted with the other grenadiers.  But then he gets into a fight with two others over a woman and kills them.

Escaping arrest, Casca takes a ship to Jamaica and while he's there, is hired by a plantation owner to find his niece who's been kidnapped by pirates.  Put on board Blackbeard's ship under cover, Casca is discovered and marooned by Blackbeard on an island.  Enlisting an Anglo-Spanish group of fugitives, they steal a ship and sail to Jamaica and find the niece and rescue her, but the plantation owner betrays Casca.  Killing him, Casca decides to stay with the niece in Jamaica for a while.

Casca's participation in the European theatre of the Seven Year's War is mentioned in the Trench Soldier.

Finally Casca leaves Jamaica and lands in North America.  The lure of a free life in the untamed wilds draws him west with fur trappers.  When Cherokee attack all the trappers are killed and Casca's healing powers impress the Cherokee.  He's taken to their village where he lives as a powerful medicine man for some years, taking the chief's daughter as his squaw.  But when smallpox decimate the village, including the squaw, the surviving Cherokee decide Casca's medicine is broken and cast him out.

He staggers into a British settlement who believe he's a survivor of an attack and take him in.  He ends up with a wealthy widow who tells him her late hisband was murdered by a French officer.  Taking payment to hunt him down, Casca ends up crossing the Atlantic to Europe and enlists in the Prussian army who are fighting the French.  When Casca finally finds the Frenchman he's told that in fact the widow and he were lovers but he had gone back to his wife and she had never forgiven him.

Casca returns to America and tells her the Frenchman died in the war.  He then buys some land and settles down but growing discontent with British rule drags Casca in and he joins the rebels, fighting at Lexington, Boston, New york and finally Yorktown where the British surrender.  Returning home he finds everything has been destroyed and he decides to travel to Europe.

There the French have had a revolution and Casca takes up the republican cockade and fights for the new regime.  Finally he comes under command of a new general, Bonaparte.