Illustration by Charles Ricketts (1866–1931) from a special edition history of England published in 1903.
Info from wiki: Agnes, Countess of Dunbar and March (née Randolph; c. 1312–1369), known as Black Agnes for her dark hair and eyes, and sallow complexion, was the wife of Patrick, 9th Earl of Dunbar and March. Agnes became renowned for her heroic defence of Dunbar Castle in East Lothian against an English siege led by William Montagu, 1st Earl of Salisbury. Salisbury’s first attempt at taking the castle centered on catapulting huge rocks and lead shot against the ramparts, but this was met with disdain by Lady Agnes, who had one of her ladies-in-waiting dust off the ramparts with her kerchief. The English were employing an enormous siege tower called a sow in an attempt to storm the castle, but the countess simply advised Salisbury that he should “take good care of his sow, for she would soon cast her pigs, meaning his men, within the fortress.” She then ordered that a boulder, which had been heaved on them earlier, be thrown down from the battlements and crushed Salisbury’s sow to pieces. At one point, having captured Agnes’s brother, John Randolph, 3rd Earl of Moray, the English threw a rope around his neck and threatened to hang him if Agnes did not surrender the castle. However, she merely responded that his death would only benefit her, as she would inherit his earldom. She was not actually in line for the earldom, so either she was taking a serious gamble with her brother’s life or the story is a later embellishment. Five months had passed since the English had come to Dunbar. Salisbury admitted defeat and lifted the siege on 10 June 1338
The failed siege of Dunbar had cost the English crown nearly 6,000 British pounds and had gotten nothing out of it. For centuries afterwards, Agnes's defense of Dunbar Castle caught the attention of contemporary chroniclers and Scottish historians due to her bravery and might.