John Frederick of Schleswig-Holstein-Gottorp (born 1 September 1579 in Gottorp, a part of today's Schleswig; died 3 September 1634 in Altkloster, a part of today's Buxtehude) was the Lutheran Administrator of the Prince-Archbishopric of Bremen, the Prince-Bishopric of Lübeck and the Prince-Bishopric of Verden.
His parents were Adolf I, Duke of Schleswig-Holstein-Gottorp and Christine, Landgravine of Hesse-Cassel. John Frederick and Anna Dobbel from Bremervörde, the Bremian prince-archiepiscopal residence, had two children: Friedrich and Christine. In 1621 Ferdinand II, Holy Roman Emperor, legitimated them and ennobled them as von Holstein.
After John Frederick's brother John Adolf succeeded their brother Philip, Duke of Schleswig-Holstein-Gottorp as Duke of Schleswig-Holstein-Gottorp, the Bremian Chapter feared that John Adolf would integrate the Prince-Archbishopric of Bremen into his inheritable ducal monarchy. The Chapter demanded that John Adolf would resign, which he did in 1596 in favour of John Frederick. In 1607 John Adolf also handed over the Prince-Bishopric of Lübeck to his brother.
At the beginning of the Thirty Years' War, John Frederick and his prince-bishoprics of Bremen and Lübeck maintained neutrality, as did most of the territories in the Lower Saxon Circle.
After 1613 King Christian IV of Denmark and Norway, being in personal union Duke of Holstein within the Holy Roman Empire, turned his attention to gain grounds by acquiring the prince-bishoprics of Bremen, Verden, Minden and Halberstadt.
He skillfully took advantage of the alarm of the German Protestants after the Battle of White Mountain in 1620, to stipulate with Bremen's Chapter and John Frederick, his cousin of second degree, to grant coadjutorship of the See of Bremen for his son Frederick, later Crown Prince of Denmark (September 1621). Coadjutorship usually included the succession of a See.
In November 1619 Christian IV of Denmark, Duke of Holstein stationed Danish troops in the Bremian city of Stade, officially on behalf of his son the provided to be Administrator successor, suppressing an unrest of its burghers.
In 1620 Christian, the Younger, titular Duke of Brunswick and Lunenburg-Wolfenbüttel, the Lutheran Administrator of the Prince-Bishopric Halberstadt requested that the Lutheran Prince-Archbishopric of Bremen would join the war coalition of the Protestant Union. John Frederick and the Bremian Estates met in a diet and declared their loyalty to Ferdinand II, Holy Roman Emperor, as well as their neutrality in the conflict.
With Danish troops within his territory, John Frederick tried desperately to keep his Prince-Archbishopric out of the war, being in complete agreement with the Estates and the city of Bremen. When in 1623 the Republic of the Seven United Netherlands, fighting in the Eighty Years' War for its independence against Habsburg's Spanish and imperial forces, requested its Calvinist co-religionist of the city of Bremen to join, the city refused, but started to enforce its fortifications.
In 1623 the territories comprising the Lower Saxon Circle decided to recruit an army in order to maintain an armed neutrality, with troops of the Catholic League already operating in the neighboured Lower Rhenish-Westphalian Circle and dangerously approaching their region. The concomitant effects of the war, debasements and dearness, had already caused an inflation also in the region. The population suffered from billeting and alimenting Baden-Durlachian, Danish, Halberstadtian, Leaguist, and Palatine troops, whose marching through the John Frederick had to tolerate in order to prevent entering into armed conflict.
In 1623 the Republic of the Seven United Netherlands, diplomatically supported by James I, King of England, the brother-in-law of Christian IV of Denmark, started a new anti-Habsburg campaign. Thus the troops of the Catholic League were bound and the Prince-Archbishopric seemed relieved. But soon after the imperial troops under Albrecht von Wallenstein headed for the North in an attempt to destroy the fading Hanseatic League, in order to subject the Hanseatic cities of Bremen, Hamburg and Lübeck and to establish a Baltic trade monopoly, to be run by some imperial favourites including Spaniards and Poles. The idea was to win Sweden's and Denmark's support, both of which since long were after the destruction of the Hanseatic League.
In May 1625 Christian IV of Denmark, Duke of Holstein was elected – in the latter of his functions – by the Lower Saxon Circle's member territories commander-in-chief of the Lower Saxon troops. More troops were recruited and to be billeted and alimented in the Lower Saxon territories, including the Prince-Archbishopric. In the same year Christian IV joined the Anglo-Dutch war coalition. In 1625 Johan 't Serclaes, Count of Tilly warned John Frederick to further accept the stationing of Danish troops and Ferdinand II, Holy Roman Emperor, demanded the immediate end of his and Verden's alliance with Denmark. Verden was already ruled by Christian's son Frederick II, Administrator of the Prince-Bishopric of Verden, being as well the intended successor of John Frederick. He declared again his loyalty to the Emperor and neutrality in the conflict.
In response, Christian IV ordered his troops to capture all the important traffic hubs in the Prince-Archbishopric and entered into the Battle of Lutter am Barenberge, on 27 August 1626, where he was defeated by the Leaguist troops under Tilly. Christian IV and his surviving troops fled to the Prince-Archbishopric of Bremen and took their headquarters in Stade. John Frederick fled to his Prince-Bishopric of Lübeck and left the rule in the Prince-Archbishopric of Bremen to the Chapter and the Estates.
By 1627, Christian IV had de facto dismissed John Frederick from the Bremian See. In the same year, Christian IV withdrew from the Prince-Archbishopric of Bremen, in order to fight Wallenstein's invasion of Duchy of Holstein. Tilly then invaded the Prince-Archbishopric and captured its southern parts. The city of Bremen shut its city gates and entrenched behind its improved fortifications. In 1628, Tilly besieged Stade with its remaining garrison of 3,500 Danish and English soldiers. On 5 May 1628 Tilly granted them safe-conduct to England and Denmark and the whole Prince-Archbishopric was in his hands. Now Tilly turned to the city of Bremen, which paid him a ransom of 10,000 rixdollars in order to spare its siege. The city remained unoccupied.
Wallenstein had meanwhile conquered all the Jutish Peninsula, which made Christian IV to sign the Treaty of Lübeck, on 22 May 1629, in order to regain possession of all his feoffs on the peninsula, he in return agreed to formally end Denmark's participation in the Thirty Years' War and waived for his son Frederick II, Administrator of the Prince-Bishopric of Verden, the administration of that prince-bishopric as well as the provided succession as Administrator of the Prince-Bishopric of Halberstadt.
John Frederick, exiled in the Imperial Free City of Lübeck, was in a markedly weak position. So in 1628 he consented that the Lutheran convent in the former Premonstratensian Our Lady's Friary in Stade – under Leaguist occupation – was restituted to Catholic rite and manned with foreign monks, if the Chapter would also agree. Again passing the buck on to the Chapter.
The Leaguist takeover enabled Ferdinand II, Holy Roman Emperor, to implement the Edict of Restitution, decreed on 6 March 1629 within the Prince-Archbishopric of Bremen. The Bremian monasteries still maintaining Roman Catholic rite – Altkloster, Harsefeld Archabbey, Neukloster, and Zeven Nunnery – became the local strongholds for a reCatholicisation within the scope of Counter-Reformation.
Under the threat of the Edict of Restitution John Frederick consented to Canonical Visitations of the remaining monasteries, those clinging to Roman Catholic rite and those converted to voluntary Lutheran convents alike. Nunneries had traditionally been institutions to provide unmarried daughters of the better off, who couldn't be provided a husband befitting their social status or who didn't want to marry, with a decent livelihood. So when an unmarried woman of that status joined a nunnery she would bestow earning assets (real estate) or – restricted to her lifetime – regular revenues paid by her male relatives, on the nunnery, making up in the former case part of the nunnery's estates (not to be confused with the political body of the Estates).