Counter-castles were built in the Middle Ages to counter the power of a hostile neighbour or as a siege castle, that is, a fortified base from which attacks could be launched on a nearby enemy castle.

In castle science, and according to mediaeval usage, a counter-castle was a type of castle that was built to secure a territorial lord's claims to power or to besiege and conquer the estates of rival rulers. In such cases, it may also be referred to as a siege castle. These terms are not used uniformly by specialist authors. Usually a distinction is made between counter-castles and siege castles. Where this is the case, a siege castle refers to one built near the enemy castle within the range of trebuchets and catapults that could act as a strongpoint, a route barrier, a refuge in the event of counter-attacks, a barracks and a battery position for ballistic weapons.

A counter-castle is often used to describe a castle that was built at a greater distance from enemy fortifications and castles. It did not support the immediate siege of a castle, but was constructed as a base in an area of rival power in order to prevent enemy attempts to expand their influence and control.

Siege castles are only evident from the period of the Late Middle Ages onwards. They were usually built as a temporary fortifications using wood and earth above the castle to be captured and within sight and the range of their guns. From this location the target would be bombarded.

Sometimes only a trebuchet position was established instead of a masonry or wooden siege castle. A favourable point in the terrain, within range of the besieged castle, was levelled and lightly fortified. From this position, the enemy castle could be engaged relatively safely with a trebuchet or catapult and its occupants psychologically ground down. Such a position may be seen today about 430 metres northeast and above Thurant Castle on the Moselle.

Trebuchets were used in sieges from the early 13th century. Large catapults had a range of about 400 to 500 metres. However, only wealthy feudal lords could finance the use of such a large, costly siege engine or even the construction of a counter-castle.

Only occasionally did the attackers have the time and financial resources to build their fortress of stone. Rare examples are Ramstein Castle, the Rauschenburg at Mermuth in the Hunsrück and Trutzeltz Castle. The last-named was built during the Eltz Feud as a counter-castle to Eltz. The Rauschenburg was also built in connection with the Eltz Feud as counter castle to the castles of Ehrenburg, Waldeck and Schöneck.

In the majority of known cases, siege castles were abandoned after the fighting and fell into disrepair. Sometimes the lord of the formerly besieged castle was given the counter-castle in a peace agreement or even took it over as a fief, as in the case of Trutzeltz Castle. In exceptional cases, such structures were - when the conquest was successful - expanded into independent castles. Examples include the Hohenfels and Schadeck Castle at Runkel on the Lahn.