The television series was first broadcast on DR1 on 12 October 2014. It was immediately criticised for historical inaccuracies. The series producer, Peter Bose, commented that "We were expecting debates but were rather surprised by the continuous bashing".
The series has a dark and bleak atmosphere despite much being photographed in wide open spaces.
It is 1851 and the people of a Danish village await the return of the victorious soldiers from the First Schleswig War. Among the soldiers is farmer Thøger Jensen (Lars Mikkelsen), who has suffered a severe leg wound and returns to his wife Karen (Sarah Boberg) and sons 12-year-old Laust (Sylvester Byder) and 11-year-old Peter (Benjamin Holmstrøm Nielsen). Also returning is Didrich (Pilou Asbæk), son of the local landowner, the Baron, who served as a captain. Didrich has been severely damaged psychologically by the war and has also been tainted by cowardice; his father reveals that he bribed his fellow officers not to report him to the military authorities. Didrich's mother died giving birth to him, and his father (Waage Sandø) has never forgiven him; while kind to his tenants, he treats his son with scorn.
Overjoyed to have their father home, Laust and Peter also befriend Inge Juel (Fanny Bornedal), the spirited daughter of the Baron's new estate manager. Didrich, too, who is increasingly becoming a dissolute alcoholic, has feelings for Inge, although she is only a child. At the harvest festival celebrations he propositions her, but she slaps his face and runs away. Later, Thøger dies from his wound, which has never healed and causes him great pain, and Laust becomes a stable boy for the Baron.
In Copenhagen, the leader of the National Liberal Party, Bishop Ditlev Monrad (Nicolas Bro), meets famous actress Johanne Luise Heiberg (Sidse Babett Knudsen), who begins to encourage him in his nationalist ideas.
The action then advances to the 1860s. Monrad, now Council President (prime minister), has become a convinced nationalist and actively tries to provoke war with Prussia over the Schleswig-Holstein Question, still encouraged by Mrs Heiberg. He tries to persuade the new king, Christian IX (Henrik Prip), that declaring war would show the people that Christian, who was born in Schleswig and grew up speaking German, is a true Dane. In Berlin, King Wilhelm (Dieter Montag), his minister-president, Otto von Bismarck (Rainer Bock), and his chief of the general staff, General Helmuth von Moltke (Heikko Deutschmann), greet Denmark's sabre-rattling with disbelief.
In the village, Laust (Jakob Oftebro) and Peter (Jens Sætter-Lassen) have grown into young men, now both in love with Inge (Marie Tourell Søderberg). A group of gypsies led by Ignazio (Zlatko Burić) arrives in the village and ask for work. Although Inge's father (Peter Gilsfort) says they need help with the harvest, Didrich orders them to leave. Later, he and his dissolute friends catch Ignazio's son, Djargo (Jordan Haj), poaching pheasant on the Baron's land and severely flog him. He is found by Laust, Peter and Inge, who take him to the Baron. The Baron chastises his son and gives the gypsies work in the harvest. He also persuades Laust and Peter and their friend Einar (Carl-Christian Riestra) to join the army.
The brothers complete their basic training and return to the village on leave, arriving at the harvest festival celebrations. They leave with Inge and both end up kissing her. However, after they leave her, Laust, on the pretext of going to search for his lost knife, returns to her without Peter's knowledge and they make love. Later, Didrich, drunk as usual and unable to find Inge, rapes Ignazio's beautiful, mute daughter Sofia (Eva Josefíková), who keeps the attack to herself.
The brothers return to the army, where they and Einar are assigned to a company of the 8th Brigade. There they befriend Alfred (Jens Christian Buskov Lund), a naive young man from Skagen, Erasmus (Esben Dalgaard Andersen), a cheerful bearded giant who is a miller in civilian life, and Johan Larsen (Søren Malling), a middle-aged veteran who has a reputation for being psychic and is soon promoted to corporal. They also form good relations with the company's second-in-command, the young Second Lieutenant Wilhelm Dinesen (Johannes Lassen), and with their senior NCO, Sergeant Jespersen (Peter Plaugborg).
Monrad's plans are finally realised when he announces that Denmark has fully annexed Schleswig and Prussia has no choice but to declare war. The 8th Brigade is sent south to occupy the Danevirke, a line of fortifications which has always been regarded as the country's southern border and which is regarded in Danish mythology as impregnable. However, when they arrive they find the Danevirke dilapidated, with no barracks accommodation. They are also assigned a new company commander to replace the former ancient and senile officer, who has died en route; it is Didrich, who has been recalled to the colours.
The company is ordered to Mysunde, where they witness the devastation of the Battle of Mysunde, the first battle of the war, although Didrich keeps them well behind the action. Laust and Peter have both been writing to Inge and she to them, but she and Laust have also been exchanging further secret letters. Peter receives one of these by mistake and realises that his brother has slept with Inge. Devastated, he disowns Laust. Didrich later promotes Johan to sergeant and Laust to corporal.
It becomes obvious to the Danish commander, General Christian de Meza (Søren Sætter-Lassen), that he cannot hold the Danevirke because the marshes and water on which he had relied to defend its flanks have been frozen solid by the hard winter, and he asks for permission to withdraw to Dybbøl, but Monrad refuses. De Meza withdraws anyway and is replaced by the unimaginative General Georg Gerlach (Kristian Halken), who is guaranteed to do anything he is told to do. Peter, Einar and Jespersen are among a small party led by Dinesen who volunteer to remain behind at the Danevirke to spike the guns after the Danish withdrawal. They escape just before the Germans arrive and are pursued by a group of German hussars, who capture them and execute one man before Dinesen, who has managed to escape, reappears and surprises them; caught off guard, all the hussars are killed by the Danes. Dinesen begins to get a reputation for ferocity and invincibility.
Meanwhile, during the retreat to Dybbøl, Didrich orders Laust to jump into a frozen pond to retrieve a cannon that has fallen in. After his friends pull him out he begins suffering from severe hypothermia and he and his friends, including Johan, Alfred and Erasmus, begin to fall further behind the column. They thereby miss the Battle of Sankelmark, although they come upon the bloody aftermath.
Back in the village, Inge realises she is pregnant by Laust. Her mother disowns her and she leaves with the gypsies when they head south to see whether they can make any profit from the war. During the journey she and Djargo realise Sofia too is pregnant and Djargo swears to kill Didrich, whom he correctly surmises has raped his sister. They reach Dybbøl, where Inge encounters Didrich, who tells her that both brothers are dead.
The Danish army digs in at Dybbøl. Both Laust's and Peter's groups arrive, although they do not encounter one another. Laust, now dying from pneumonia, is taken to a military hospital where Inge and Sofia are working as nurses, although they do not meet. Djargo disguises himself as a soldier to try to kill Didrich, but is caught. Didrich wants him executed, but Jespersen persuades him that this would be a crime and he instead has him locked in a dugout. Dinesen leads his group in a nighttime raid to kill the German bandsmen who have been playing marches near the Danish lines. Celebrating after the successful raid, Alfred, who has joined the group, has too much to drink and climbs onto the parapet, where he has both hands blown off by an exploding shell. He later dies of blood loss in hospital, where Inge and Peter pass next to each other but do not notice the other. Johan mysteriously manages to cure Laust of his pneumonia and he returns to the company.
Finally, the Germans attack, beginning with a remorseless six-hour artillery barrage. They are now commanded by the highly competent Prince Friedrich Karl (Barnaby Metschurat), the Prussian king's nephew, who has replaced the 80-year-old and increasingly senile Field Marshal von Wrangel (Hans-Michael Rehberg). Most of Didrich's company are holding the trenches, although Dinesen's men are with the main body of the brigade who are forming a reserve behind the lines. The German infantry attack and Erasmus is killed. Djargo, who has escaped during the barrage, finds Didrich and stabs him in the thigh, but is killed by a stray bullet before he can finish off his sister's rapist. Didrich, terrified and cowering, surrenders to the Germans, but they ignore him.
The 8th Brigade attacks, led by Dinesen after its commanding officer refuses to advance without orders from his superiors, and manages to push the Germans back temporarily. A German counterattack, however, destroys the brigade and kills Jespersen, and Peter, trapped behind enemy lines, finally realises that he has to find his brother. Meanwhile Laust has discovered the wounded and frightened Didrich and begins carrying him to safety. However, he is spotted and shot dead by the Germans. Peter, arriving too late but witnessing his brother's death, falls into shock and is captured and confined to a prisoner of war hospital in Austria. Meanwhile, Inge gives birth as the battle rages. Realising his country is defeated, King Christian surrenders, although Monrad, abandoned by Mrs Heiberg, still tries to persuade him to continue fighting.
Johan infiltrates the German lines the night after the battle and collects all the papers, letters and photographs from the bodies of his dead comrades. He then travels throughout Denmark handing them to their families. When he reaches Laust and Peter's village he tries to give Laust's last letter to Inge, who has been taken back in by her parents, but her mother Ingrid (Helle Fagralid) refuses to let him see her and later reads and burns the letter without giving it to her. The Baron asks Johan about Didrich, who is in a prisoner of war camp in Hamburg, and Johan bitterly tells him the truth: that his son is a coward and a deserter. As he leaves, the Baron shoots himself.
Later Didrich is released and returns to the village, to find himself the new Baron. He asks Inge to marry him, implying an estate manager's daughter would be a fool to refuse such an offer from a nobleman. Still believing both Laust and Peter to be dead, she accepts, although she becomes hysterical when her child, whom she has named Laust after his father, is taken from her; Didrich has made it clear that he does not want another man's bastard.
Two years later, Peter, now sane, fit and healthy once more, is finally released and works his way back across Austria and Germany to Denmark, encountering en route German troops now marching to fight their former allies, the Austrians. He returns to the village to find Sofia and her baby, whom she has named Peter after him, living with his mother. He goes to see Inge, who, pregnant with her and Didrich's first child, breaks down when she sees him and realises Didrich lied to her. Peter knocks a typically offensive Didrich down and leaves. He finds little Laust in the orphanage in which he has been abandoned and adopts him as his own son. He falls in love with and marries Sofia, who is now capable of at least limited speech, celebrating with his family and friends, including Einar, who has also survived the war. Monrad and his family make plans to leave for New Zealand. Inge's voiceover tells us that she and Didrich had a number of children, each of whom seemed to calm him a little more, although he was never truly normal.
A parallel and linked story takes place in the modern day. Troubled teenage tearaway Claudia (Sarah-Sofie Boussnina) and her drug dealer boyfriend Zlatko (Besir Zeciri) are taken on a school trip to the Dybbøl battlefield, where they are bored and smoke marijuana. Soon afterwards Claudia, whose brother was killed while serving in the army overseas (probably in Afghanistan) and whose parents have retreated into depression, leaves school and is found a temporary job as carer for Baron Severin (Bent Mejding). In his nineties, nearly blind, confined to a wheelchair and probably suffering from dementia, Severin lives alone in his mansion, which it is soon clear is the same mansion formerly owned by Didrich. While looking for things to steal to finance her boyfriend's drug dealing, Claudia finds a handwritten journal, which turns out to be Inge's memoirs, written just before her death in 1939. Inge was Severin's grandmother and he asks Claudia to read it to him. She begins reluctantly, but soon warms to the story and to the old man, and it is this story, read by both Claudia and Inge, that forms the voiceover at various points in the series. Later she discovers that through her mother she is Sofia's great-great-great-great-granddaughter and that she and Severin are therefore distant cousins (presumably her great-great-great-grandfather was little Peter, who was Didrich's son, as was Severin's father). She tries to sell the jewellery she has stolen from Severin, but the jeweller becomes suspicious and calls the police and she flees back to the mansion. Tearfully she admits to Severin what she has done, but he says he knows and forgives her. As she reads the end of the story to him, she realises that he was with Inge at the end and wrote the whole thing down for her. Excitedly she asks him about it, but then realises that the old man has died as she was reading.
The following is a list of significant cast members from the series:Esben Dalgaard Andersen as Erasmus
Pilou Asbæk as Didrich
Peter Benedict as Lieutenant-General Edwin von Manteuffel
Rasmus Bjerg as Colonel Max Müller
Sarah Boberg as Karen Jensen
Rainer Bock as Otto von Bismarck
Fanny Bornedal as Inge Juel (12 years old)
Sarah-Sofie Boussnina as Claudia Henriksen
Nicolas Bro as Bishop D. G. Monrad
Zlatko Burić as Ignazio
Sylvester Byder as Laust Jensen (12 years old)
Heikko Deutschmann as Lieutenant-General Helmuth von Moltke
Karel Dobrý as Major-General August von Goeben
Helle Fagralid as Ingrid Juel
Barbara Flynn as Queen Victoria
James Fox as Lord Palmerston
Peter Gilsfort as Inge's Father
Jordan Haj as Djargo
Kristian Halken as Major-General Georg Gerlach
Stig Hoffmeyer as Hans Christian Andersen
Olaf Johannessen as Carl Christian Hall
Eva Josefíková as Sofia
Sidse Babett Knudsen as Johanne Luise Heiberg
Johannes Lassen as Second Lieutenant Wilhelm Dinesen
Lars Lohmann as King Frederick VII of Denmark
Jens Christian Buskov Lund as Alfred
Søren Malling as Johan Larsen
Bent Mejding as Baron Severin
Barnaby Metschurat as General Prince Friedrich Karl
Louise Mieritz as Emilie Lütthans
Lars Mikkelsen as Thøger Jensen
Dieter Montag as King Wilhelm of Prussia
Benjamin Holmstrøm Nielsen as Peter Jensen (11 years old)
Jakob Oftebro as Laust Jensen
Søren Pilmark as Major E. A. Lundbye
Peter Plaugborg as Sergeant Jespersen
Henrik Prip as King Christian IX of Denmark
Rainer Rainers as Johann Gottfried Piefke
Hans-Michael Rehberg as Field Marshal Friedrich Graf von Wrangel
Carl-Christian Riestra as Einar
Adam Ild Rohweder as Lieutenant Viggo Monrad
Waage Sandø as the Baron
Jens Sætter-Lassen as Peter Jensen
Søren Sætter-Lassen as General Christian de Meza
Philip Schenker as Lieutenant-General Eduard Vogel von Falckenstein
Roland Schreglmann as Ludwig
Marie Tourell Søderberg as Inge Juel
Jens Jørn Spottag as Major-General Glode du Plat
Troels Malling Thaarup as Ernst Schau
Ludwig Trepte as Heinz
Besir Zeciri as Zlatko
The series divided reviewers in Denmark; some were enthusiastic while others considered the cost should have been used for other programming, especially more Scandinavian noir.
The series claims that German Confederation was involved in the war, although in reality the German Confederation did not take part in the war and in fact called the war illegitimate.
The series premiered on Irish public service broadcaster RTÉ2 in July 2015 and on Swedish commercial broadcaster TV4 in June 2015. It was also broadcast by the Franco-German network Arte in June 2015. 1864 was broadcast in a four week run on BBC4 in the UK, starting on 16 May 2015 with 2 episodes shown each week. The series was shown in Australia on SBS-TV, commencing on 7 June 2016.