Inverted Wedge
Inverted Wedge (two up; Ger. Breitkeil), a tactical formation with two manoeuvre elements in front and one in reserve behind; as opposed to the wedge. S. German Infantry Tactics.
When attacking in inverted wedge formation, it must be determined which of the two up elements has the lead.
Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909