Both branches used in their arms the two lions of Brunswick, the blue lion of Lüneburg and the white steed of Saxony. The use of the lion as a heraldic animal in the House of Guelph goes back to Henry the Lion in the 12th century at least. However, Henry used only a single lion as his symbol. Later accounts by medieval writers that the two golden lions of Brunswick were granted to Henry by the English king, his father-in-law, are deemed fictional by modern historians. It were Henry's sons from his marriage with Matilda of England, the future Holy Roman Emperor Otto IV and Henry V, Count Palatine of the Rhine, who adapted the Royal Arms of England to display their royal lineage. While Otto's coat of arms showed the three golden lions of England, Henry used only two. The two lions of Henry V then went on to become the symbol of the House of Guelph. The blue lion of Lüneburg was adopted by John I of Lüneburg, who based his coat of arms on the coat of arms of Denmark to emphasise his kinship with the Danish kings. The dukes of Brunswick later added the blue lion to their arms as well, to show their own claim to the territory of Lüneburg.