Eustace IV was a nobleman from the 12th century, known as the son of King Stephen of England and Matilda of Boulogne. He was born around 1130 and became the Count of Boulogne. Eustace played a significant role in the civil war known as the Anarchy, which was a conflict over the English throne between his father and Empress Matilda, the daughter of Henry I of England. Eustace IV's ambitions included claiming the English throne, but he faced challenges due to his father's unstable reign. He died in 1153, before he could achieve his goals, and his death led to a shift in power dynamics, ultimately paving the way for Henry II to ascend the throne.