[2] Around 1162 Gerald assembled a private army (a mesnada) and rapidly developed tactics that proved remarkably successful in seizing Muslim strongholds, though it was not adapted for siege warfare.

[3] He "perfected techniques of nocturnal surprise in wintry or stormy weather, stealthy escalading of walls by picked commando-like troops, cutting down of sentries and opening of town gates to the larger force stationed without.

"[4] Among the primary sources for Gerald's methods the most important is the contemporary Arabic chronicler Ibn Ṣāḥib al-Ṣalā, whose Al-Mann bil-Imāma was incorporated into the history of al-Maqqarī in the seventeenth century.

[5] His opinion of Gerald and his tactics is very low: The dog [Gerald] marched on rainy and very dark nights, with strong wind and snow, towards the cities and, having prepared his wooden instruments of scaling [walls] very large, so that they would surpass the wall of the city, he would apply those ladders to the side of the tower and catch the sentinel [by surprise] and say to him: "Shout, as is your custom," in order that the people would not hear him.

Ibn Ṣāḥib's version goes: In the second Jumada al-awwal [15 April–13 May] of the anno Hegirae 560 [1165] the city of Trujillo was surprised, and in Dhu al-Qi'dah the notable village of Évora.

[9] All the primary sources agree that Santa Cruz de la Sierra was the last of Gerald's successes, which may place it as late as 1169,[10] though perhaps earlier (1167/8), along with Ureña.

[10] The Leonese king, Ferdinand II, son of Alfonso VII, took action immediately after the taking of Cáceres, probably early in the spring of 1166, capturing Alcántara later that year and thus securing a crossing over the Tagus.

[4] Seeing an opportunity to add to his domains the chief city of the region at the expense of both his Muslim and Christian enemies, Afonso I of Portugal came with an army to Badajoz to relieve his nominal vassal.

He was the king's brother-in-law, being married to Stephanie the Unfortunate, an illegitimate daughter of Alfonso VII by his second mistress, Urraca Fernández, and thus a half-sister of Ferdinand II.

Ferdinand succeeded in gaining the valley of the upper Limia and the regions of Toroño (around Tuy), Capraria (around Verín), and Lobarzana (around Chaves) from Afonso in exchange for his release.

[15] In 1171 and 1172,[16] while Yusuf was waging war on Valencia and Murcia, general anarchy prevailed in the Extremadura as Leonese, Portuguese, and Almohad troops fought for supremacy.

[25] The legends which later arose surrounding Gerald are given concise retelling by Louis-Adrien Duperron de Castera, a French translator: He was a man of rank, who, in order to avoid the legal punishment to which several crimes rendered him obnoxious, put himself at the head of a party of freebooters.