Striped Shield: In the chronicle by Petrus of Ebulo dating from 1194/97, the knights who take Richard I (Lionheart) captive, bear shields with horizontal bars ("gules a fess argent"). The first evidence for this design being used in the coat of arms of an Austrian duke is a seal of Duke Friedrich II on a document for Lilienfeld (Lower Austria) dating from November 30, 1230. After that, the striped (or barred) shield was used by the Austrian dukes, including Přemysl Otakar II, as their coat of arms, instead of the one-headed eagle which has become known as the symbol of "Neu-Oesterreich" since Rudolf IV, as opposed to the coat of arms showing five eagles ("Alt-Oesterreich"). The Lower Austrian Estates also used both coats of arms. In 1804, the striped shield became the centre of the coat of arms of the Austrian monarchy; in 1919, the Red-White-Red colour combination was adopted for the flag of the newly-founded Republic and combined with the one-headed eagle in the Austrian national coat of arms.
The origin of the barred shield is not clear, the legend that it originated during the siege of Acre was first told in the late 14th century in "Oesterreichs Chronik von den 95 Herrschaften" (Austrian Chronicle of the 95 domains) by L. Stainreuter.
Literature#F. Gall, Oesterreichische Wappenkunde, 1977.