The event that marked the beginning of the English Reformation was the break with the Roman Catholic Church by King Henry VIII. This event had significant political and religious implications for England and led to major changes in the country's religious landscape.

Background:
- Prior to the English Reformation, England was a predominantly Catholic country, with the Roman Catholic Church holding significant power and influence.
- King Henry VIII ascended to the throne in 1509 and initially maintained a strong allegiance to the Catholic Church, even earning the title "Defender of the Faith" from Pope Leo X for his defense of Catholic doctrine against Martin Luther's Protestant Reformation.

Desire for an Annulment:
- However, Henry VIII's desire for a male heir to secure the Tudor dynasty led him to seek an annulment of his marriage to Catherine of Aragon, as she had failed to produce a male heir.
- The Catholic Church, under the authority of the Pope, refused to grant the annulment, as it went against their doctrine.
- This refusal prompted Henry VIII to take matters into his own hands and seek a break with the Catholic Church.

Break with the Catholic Church:
- In 1533, Henry VIII secretly married Anne Boleyn, and the following year, Archbishop Thomas Cranmer declared Henry's marriage to Catherine null and void.
- In 1534, the Act of Supremacy was passed, declaring the King to be the Supreme Head of the Church of England, effectively severing ties with the Pope and the Roman Catholic Church.
- This act also required all subjects to swear an oath of allegiance to the King as the head of the Church.

Consequences and Impact:
- The break with the Catholic Church marked the beginning of the English Reformation, as it initiated a process of religious reform in England.
- Henry VIII dissolved monasteries, confiscated their wealth, and used the funds to strengthen his own power and control.
- The English Church, now under royal control, began to adopt Protestant doctrines and practices, although it retained some Catholic elements.
- The English Reformation would continue to evolve under Henry's successors, Edward VI, Mary I, and Elizabeth I, with each monarch having their own religious policies and influences.

Conclusion:
The break with the Roman Catholic Church by King Henry VIII marked the beginning of the English Reformation. This event had significant political and religious implications for England, leading to the establishment of the Church of England and the subsequent adoption of Protestant doctrines and practices.