Algeria–Libya border

France occupied much of the northern coastal areas of Algeria in the period 1830–47, which had hitherto been subject to the nominal control of the Ottoman Empire.

[2] For most of the 19th century the coastal region of modern Libya (organised as the Vilayet of Tripolitania) was part of the Ottoman Empire, though with a large degree of de facto autonomy.

[6][2] France and Italy signed a treaty on 12 September 1919 which delimited a boundary between Algeria and Libya.

[3][2] During the North African Campaign of the Second World War Italy was defeated and its African colonies were occupied by the Allied powers, with Libya split into British and French zones of occupation.

Relations since independence have largely been cordial, though the border remains generally insecure due to the impact of terrorism and spill-over from the Libyan Civil War.