During the Thirty Years' War, which began after Ferdinand took the imperial throne in 1619, Nicolae and Radu Șerban joined a Habsburg coalition against Gabriel Bethlen's Transylvania.

In a document which uses the courtly language, Church Slavonic, Nicolae describes himself as: Млстію Вжією Іѡ Нєколає Воєвода и гспднь въсою зємлє ꙋггровлахискоє ("By the Grace of God Io Niecolaie Voivode and Hospodar of the Entire Hungro-Wallachian Country").

[4] Scholar Ștefan Mihăilescu believes that Michael the Brave may have named his son in direct homage to Saint Nicholas, whom he credited as his personal protector.

[5] A period witness and biographer, Balthasar Walther, contrarily reports that Pătrașcu celebrated his name day on the Feast of Saint Peter (June 29).

[14] Various scholarly disputes surround the origins of Nicolae's father Michael the Brave, or Mihai Viteazul, who passed himself off as a son of Pătrașcu the Good, from the Drăculești princely clan, and therefore also as a half-brother of Petru Cercel.

[44] From such accounts, scholar Nicolae Bălcescu deduces that he was Pătrașcu's tutor—a claim seen as inaccurate by historian Dan Simonescu, who finds it more likely that Walther was a diplomatic envoy.

Upon receiving news of Wallachia's rapprochement with the Ottomans, Transylvanian Princess Maria Christina ordered Michael's entire family to be quietly arrested.

[50] The project was suppressed when Sigismund Báthory refused to commit to the Holy League, prompting Michael to seek a matrimonial alliance with the Habsburgs and Hohenzollerns.

[64] As noted by Iorga, Nicolae's "full and uncontested" rule over Wallachia was meant to free Michael's had in claiming the throne of Transylvania (where he was formally governor on behalf of the Habsburgs).

Andronikos Kantakouzenos, Nicolae's putative uncle, was reportedly his tutor;[67] he also managed the country's fiscal affairs, as Vistier, while Miroslav of Râfov was Logothete.

[78] A contemporary testimony by the Polish diplomat Andrzej Tarnowski argues the same, namely that Michael expected Sigismund Vasa to recognize "Wallachia, Moldavia and Transylvania [as belonging] to his son Nicolae, and to his heirs of the male gender.

[87] In July, Michael requested from Rudolf that he and Nicolae be recognized as joint rulers of all three countries, and that their dynasty, including female descendants, be left to rule "to the end of time".

[88] Over those months, however, Michael had lost Transylvania to an insurgency headed by the Imperial warlord Giorgio Basta, and assisted by the Hungarian nobility; Moldavia was also reconquered by the Poles and the Movilești (see Battle of Mirăslău, Moldavian Magnate Wars).

Shortly before the battle of Bucov, he pledged to send Stanca and his children, including Nicolae, as hostages to Transylvania, hoping to secure a truce with Basta.

[89] Michael obtained guarantees that his family would not be imprisoned by his enemies, the Transylvanian Saxons, but Basta denied his other requests, including that they would be dispatched to Făgăraș Citadel.

An avviso of October 6 claims that Basta's troops ran into Michael's family not at Făgăraș, but at Huszth, which indicates that they had been moved to Partium by the retreating Hungarians, probably through Moldavia.

[104] As reported by Gane, Stanca and Nicolae remained harshly critical of Michael in their interviews with Basta and David Ungnad, accepting that he may have been guilty of conspiracy against the Holy League.

[112] In August, Nicolae addressed the Emperor a letter which reaffirmed his loyalty and asked to be received at the court in Prague, while also issuing a claim to Michael's confiscated assets.

[113] On September 28, Nicolae was at Șcheii Brașovului, where he donated various assets to St. Nicholas Church, in exchange for regular memorial services honoring his late father.

[125] In 1606, the Aulic Council settled his outstanding debt of 20,000 thaler, but he continued to be pressed by his creditors; six years later, he resold to Emperor Rudolf his father's golden necklace.

The expedition, finally started in 1616, was blocked by the hostile Transylvanian regime of Gabriel Bethlen, who joined with Iskender Pasha and defeated the Wallachian returnees in Moldavia.

The news were poorly received by Nicolae, who complained that the inquiry would open the record to "calumnies" against his father and cement Basta's depiction of the Prince as a "traitor".

[139] During that interval, both former Princes became involved in the project to assist the Maniot revolt in Ottoman Greece, with the Duke of Nevers asking them to support his "Christian Militia", which also fought against Bethlen.

[140] In November 1619, Nicolae and Graziani assisted George Druget's attack on Bethlen's Transylvania, also transferring exorbitant sums to Sigismund Vasa in exchange for his Lisowczycy (see Battle of Humenné).

[165] Mihai, who was also recognized as a Cup-bearer, stated a claim to his share of the Coiani inheritance, demanding in particular 4,000 Goldgulden pledged by the Empire to his maternal grandmother, Elena Șerban.

After his failure with Mihai Pătrașcu, Prince Matei hoped to adopt Istratie, but met opposition from the other boyars, and was ultimately discarded in favor of Diicul Buicescul.

Cernovodeanu proposes that this heraldic distinction highlighted the difference of weight in dynastic claims: Nicolae saw himself as descending from the original House of Basarab, whereas his ally was only related to the Craiovești.

[182] However, all seals used by Nicolae, Radu Șerban and Mihai Pătrașcu feature the same display, including lions in supporters and the cross (either behind the bird or in its beak), but without a ring.

Its complex field has the Wallachian bird alongside the Moldavian aurochs, two lions affrontés, and a variant of the nova plantatio theme, with both Princes in supporters.

[184] Among the specialists involved, archivist Aurelian Sacerdoțeanu proposed that the seal was designed by Nicolae in a bid to cement his claim as Michael's successor on the Moldavian throne.