Pile barrage

[3][4][5][6] Such have been used since pre-history to prevent enemy watercraft from entering waterways or harbors, etc, as to protect the sailing routes to trading posts and settlements.

[7] The Old Norse name for the structure was an ablaut-form cognate to "stake" – Old West Norse: stik, stika;[7] Old East Norse: stœk, stækh; surviving as Danish: steg, dialectally: stege, Norwegian Nynorsk: stik, stike, Swedish: stäk, steg, stig, stag, dialectally: stika, stiku; variously meaning pole, stake etc, including strait, and archaicly pile barrage etc.

[14][7] According to the Old Norse-Icelandic rendering of Historia Regum Britanniae: Breta sögur ("Sagas of the Britons"), the Britons had stakes, armored with lead and iron, driven into the river Thames, in order to protect themselves from the Roman fleet: "hann let stik gera i ana Temps" ("he had a "pile barrage" made in the Thames").

In Snorri Sturlason's Heimskringla, it is told how Harald Fairhair, around 870-900, who had recently succeeded in uniting Norway, intended to expand his empire with attacks in the Göta river (Old Norse: Gautelfur).

He then steered his ships up the River and docked at "stikin" (the pile barrage), ravaged both banks and burned the countryside.

[7] In Saint Olaf's Saga, "stik" (pile barrages) is mentioned regarding defensive measures in the unidentified lake "Lagen" in Sweden.

[7] The Danish historian Saxo Grammaticus mentions that, in the 1150s, the Danes blocked bays and fjords with long piles against the Slavic pirate ships (see Wends).

[7] Baggensstäket ("the Baggen stake") in the Stockholm archipelago is named the "Harustik" in the Danish Census Book's itinerarium from 1231.