Final answer:
John Cabot embarked on his first exploration in 1497, reaching Newfoundland and establishing England's claim to North American lands.
Step-by-step explanation:
John Cabot left for his first exploration in 1497. Commissioned by King Henry VII of England, Cabot sailed from England in May 1497 to find a northern route to Asia. He reached land, which he called Newfoundland, in June and claimed it for Henry VII. This voyage not only marked England's first foray into overseas exploration but also gave England a claim to the North American mainland, setting the stage for future colonization efforts in the New World.