Matilda landed at Arundel on 30 September 1139, launching her military campaign against King Stephen.
On 30 September 1139, Matilda landed at Arundel Castle in England, accompanied by her half-brother Robert, Earl of Gloucester, and a small force of knights, marking the beginning of her direct military campaign to depose King Stephen and claim the English throne for herself.
She was received at Arundel by her stepmother, Queen Adeliza, and — in a moment emblematic of the era's chivalric conventions — was controversially permitted safe passage by Stephen himself to join Robert of Gloucester's stronghold at Bristol, a decision that would haunt Stephen's cause for years afterward.
This landing formally opened the armed phase of the civil war known as the Anarchy, a conflict that would devastate large parts of England through the 1140s. Matilda's decision to come to England in person, rather than direct the campaign solely from Normandy or Anjou, demonstrated her personal commitment to asserting her claim and her willingness to take direct political and physical risks unusual for a royal woman of her time. From this landing, she established a base of operations in the West Country, from which her forces would contest control of the kingdom for over a decade, culminating eventually in her son's accession as Henry II.