Fort Gillingham, also known as Gillingham Fort, was constructed in 1669 on the south bank of the River Medway

River Medway

The River Medway, which is almost entirely in Kent, England, flows for from just inside the West Sussex border to the point where it enters the Thames Estuary....

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In conjunction with Cockham Wood Fort

Cockham Wood Fort

Cockham Wood Fort was constructed in 1669 on the north bank of the River Medway.In conjunction with Fort Gillingham it took on the role of defending Chatham Dockyard from seaborne attack, a role which had been performed by Upnor Castle for the previous hundred years.The fort was abandoned around...

 it took on the role of defending Chatham Dockyard from seaborne attack, a role which had been performed by Upnor Castle

Upnor Castle

Upnor Castle is an Elizabethan artillery fort located in the village of Upnor, Kent, England. Its purpose was to defend ships moored "in ordinary" on the River Medway outside Chatham dockyards....

for the previous hundred years.

Fort Gillingham was demolished long ago, but its ramparts and ditches are clearly shown on the 1869 O. S. map and the site identified as a coastguard station.

The site of Fort Gillingham is presently known as Gillingham Pier.