During 1652–1653, Zrínyi was continually fighting against the Ottomans – nevertheless, from his castle at Csáktornya (Čakovec) he was in constant communication with the intellectual figures of his time; the Dutch scholar, Jacobus Tollius, even visited him, and has left in his Epistolae itinerariae a lively account of his experiences.
Tollius was amazed at the linguistic resources of Zrínyi, who spoke Croatian, Hungarian, Italian, German, Ottoman Turkish and Latin with equal ease.
Zrínyi's Latin letters (from which it was gathered that he was married a second time, to Sophia Löbl) are, according to the Encyclopædia Britannica Eleventh Edition of 1911, "fluent and agreeable, but largely interspersed with Croatian and Magyar expressions".
In a Latin letter from 1658 to friend Ivan Ručić expressed his consciousness of being an ethnic Croat and Zrinski ("Ego mihi conscius aliter sum, etenim non degenerem me Croatam et quidem Zrinium esse scio").
In 1663, the Ottoman army, led by Grand Vizier Köprülü Ahmed, launched an overwhelming offensive against Royal Hungary, ultimately aiming at the siege and occupation of Vienna.
The Imperial troops under Raimondo Montecuccoli remained inactive while Zrínyi hastened to relieve the castle, refusing all assistance, with the result that the fortress fell.
The Peace of Vasvár laid down unfavourable terms, including a tribute to the Sublime Porte (which would never be paid) against a few presents from the Ottomans - all despite the fact that Austrian-Hungarian troops maintained the upper hand.
[11] Zrínyi rushed to Vienna to protest against the treaty, but his view was ignored; he left the city in disgust, after assuring the Venetian minister, Sagridino, that he was willing at any moment to assist the Republic against the Ottoman Empire with 6,000 men.
While no conclusive evidence has ever been found to support this claim; however, it remains true that both the Habsburgs and the Ottomans lost their mightiest adversary in Hungary due to his death.
Many criticized the indiscriminate use of foreign words and seemingly careless metres of the work; however, it was also much praised for its poetic strength, which made Zrínyi the most notable Hungarian poet of the 17th century.
The Peril of Sziget has drawn comparisons with the other Baroque epics of the period and despite its obsolete language being difficult to interpret to the average reader remains, to this day, one of the few pre-19th century Hungarian literary works still widely known to the public.
In his essays and manifestos, such as Ne bántsd a magyart – Az török áfium ellen való orvosság (Do not hurt the Hungarians - An antidote to the Turkish poison) or Mátyás király életéről való elmélkedések (Reflections on the life of King Matthias) he makes a case for a standing army, moral renewal of the nation, the re-establishment of the national kingdom, the unification of Royal Hungary with Transylvania, and, of course, the ousting of the Turkish occupants.