Blackrath Castle, seven miles south of Kilcullen, and its lands were originally leased by the Eustaces from the Wesleys of Narragh, the tenant in 1536 being a William Eustace probably from the Mainham branch. He seems to have had a son Richard who died in 1613 and a grandson Oliver who married Joan, the daughter of Walter Archbold of Timolin. Oliver is listed as one of the important men in the County was a juror in 1608 and that year was appointed Constable of Blackwood Castle. (Blackwood Castle, 8 miles north of Naas, stood forfeited by James son of Sir Pierce FitzGerald who rebuilt it in 1584. It was restored to James in 1609. His daughter Eleanor married Maurice Eustace of Newland.) Oliver Eustace died in 1640, his lands by then apparently being held in fee, but were forfeited by his sons Richard and Oliver the following year.

Part of the estate, later called Ballymount or Ballymonte, was granted to the Lord Chancellor who gave it to his brother William. It was mortgaged by William’s son Sir John in about 1687 but redeemed by the three heiresses who shared the rents. Clotilda’s share was sold in 1797 by her grandson. The site of the castle is now occupied by a farmhouse.

Blackrath immediately north of Castlemartin, rather surprisingly, seems never to have had any connection with the Eustaces.

When Christopher Eustace of Ballycotelan was executed in 1537 and his estates forfeited after the Silken Thomas rebellion, those of his lands lying west of Ballymore Eustace and south of the Liffey were granted to other members of the family; Brannockstown and Boleybeg to Maurice of Castlemartin in 1547; and Rochestown, Gaganstown and probably part of Ardinode (just east or it) to 1st Viscount Baltinglass who had done much to quell the rebellion. (Maurice’s grandson, Oliver is described as ‘of Ballycotelan" but must have been a tenant only, for I do not think that this townland ever came back to the family.)

Their subsequent history appears to have been as follows.

Brannockstown originally extended further to the west, and before the foundation of New Abbey probably adjoined Nicholastown. It passed from Maurice to his great-great-grandson the Lord Chancellor. He bequeathed it in 1665 to his nephew Sir John, who lived there until 1685, when he had to leave soon after the accession of James II during whose reign it was lost either by sale or seizure by the king. In 1700, when it was in the possession of Sir Patrick Trant, Sir Maurice Eustace, Sir John’s brother, claimed without success to have it returned to the family. An old graveyard marks the site of the chapel of St. Sylvester (venerated 10th March) which was affiliated to the parish church of Gaganstown, The Eustaces supplied the priest under the original grant.

Boleybeg including Colewels and Loughbrattock formed part of the Castlemartin lands from 1547 till sold to the widow of Alexander Eustace of Newland (see Castlekeely) in about 1675 and were forfeited by her son Lawrence in 1700. Richard, brother of the 2nd Viscount is described as "of Little Boleys" in 1547, but this may well refer to the Boleybeg some five miles north-east of Tullaghgorey near Athy, which he is known to have occupied. William Eustace, ancestor of the Robertstown line is also so described, but was presumably a tenant only.

Gaganstown (Yagageston) with Rochestown seem to have passed to Nicholas Eustace of Kerdiffstown doubtless as the dowry of Ann; daughter of the 1st Viscount, on her marriage to Nicholas in about 1538. It was forfeited by his son after the 1580 rebellion and let in 1584 to Mary Heron, daughter of Christopher, Baron of Howth. In 1599 the lands were granted in perpetuity to Joan Taaffe, daughter of Christopher Eustace who was the original owner and had been executed in 1537. They were unsuccessfully claimed on slender evidence by Roland Eustace of Blackhall in 1618. (From 1562 until the forfeiture in 1582, he seems to have occupied it but as a tenant only). The Castle and house (in ruins in 1618) have gone, but the old graveyard marks the site of the church of the former parish of Gaganstown. This included Ardinode, Boleybeg, and Moorhill, with the chapels of Brannockstown and Gilltown, south-west of Grangemore. Rochestown must have been sold by the heirs of Joan Taaffe, for it (with Brannockstown) later always formed part of the Harristown estate.

Ardinode must have been retained by the Baltinglass Viscounts and after forfeiture came into the hands of the Borrowes family. We have seen that Elizabeth, daughter of John Borrowe married Charles Eustace of Naas (see Eustaces of Robertstown), and two of her grandsons were described as of Ballymore Eustace, which is close by. Their line however died out.

These two townlands, both about five miles south of Kilcullen, though in different parishes, have sometimes been confused owing to their many different spellings. Calverstown was occupied by the Eustaces at a very early date when they built their Blackhall Castle south of the present village. John FitzMaurice of Blackhall was High Sheriff in 1400 and 1402, and was one of the twelve delegates chosen in 1404 to control the defenses of Kildare. He was probably the son of Sir Maurice of Ballycotelan. (See Coghlanstown). In 1484 and again in 1493, a Richard Eustace of Kilgowan (just east of Catverstown) was Sheriff.

Both Calverstown and Gormanstown were owned by the Viscounts Baltinglass and Roland, later the 2nd Viscount, lived at the latter while his father was alive and occupying Harristown. At this time Calverstown was leased to a William Eustace, a juror in 1536. Both Calverstown (which contained ‘two castles prostrate") and Gormanstown were forfeited after the Baltinglass rebellion, but Calverstown was re-granted to John Eustace (son of William of Castlemartin), with Harristown and Rochestown, and this grant was confirmed to his son Maurice in 1627. Sir Maurice gave or lent it (with Blackrath, two miles to the south-east) to his brother William, who lived in Dublin, but used Blackrath as a country residence. On his death in 1674 he bequeathed Calverstown to his daughter, Mary, or perhaps more probably, Sir Maurice had given it or lent as a dowry on her marriage, a few years before, to Sir Richard Dixon. On his death in 1684, it passed to his son, then only ten years old, but later to Colonel Robert Dixon M.P.of Harristown from 1703 to 1713. On his death in 1725 it passed to his nephew, Robert Dixon and thence to his sister Elizabeth, who had married Sir Kildare Borrowes, Bart. of Gilltown for Harristown in 1721, but in 1747, it had to be sold to pay debts.