HMS Unity was a 42-gun fourth-rate

Fourth-rate

In the British Royal Navy, a fourth rate was, during the first half of the 18th century, a ship of the line mounting from 46 up to 60 guns. While the number of guns stayed subsequently in the same range up until 1817, after 1756 the ships of 50 guns and below were considered too weak to stand in...

 ship of the line

Ship of the line

A ship of the line was a type of naval warship constructed from the 17th through the mid-19th century to take part in the naval tactic known as the line of battle, in which two columns of opposing warships would manoeuvre to bring the greatest weight of broadside guns to bear...

 of the English

Kingdom of England

The Kingdom of England was, from 927 to 1707, a sovereign state to the northwest of continental Europe. At its height, the Kingdom of England spanned the southern two-thirds of the island of Great Britain and several smaller outlying islands; what today comprises the legal jurisdiction of England...

 Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

, formerly the Dutch warship Eendracht, captured from the Dutch

Dutch Republic

The Dutch Republic — officially known as the Republic of the Seven United Netherlands , the Republic of the United Netherlands, or the Republic of the Seven United Provinces — was a republic in Europe existing from 1581 to 1795, preceding the Batavian Republic and ultimately...

 on 22 February 1665 by the English warships Yarmouth, Diamond and Mermaid.

Unity was commissioned on 1665 under Captain Thomas Trafford. In 1667 she became a guard ship at Sheerness

Sheerness

Sheerness is a town located beside the mouth of the River Medway on the northwest corner of the Isle of Sheppey in north Kent, England. With a population of 12,000 it is the largest town on the island....

, but was recaptured by the Dutch warship Vrede during the Raid on the Medway

Raid on the Medway

The Raid on the Medway, sometimes called the Battle of the Medway, Raid on Chatham or the Battle of Chatham, was a successful Dutch attack on the largest English naval ships, laid up in the dockyards of their main naval base Chatham, that took place in June 1667 during the Second Anglo-Dutch War...

in June 1667.