Thierry led a force of 300 mounted men-at-arms and 1,500 infantrymen to Axspoele on 19 June to lay siege to a castle held by one of William's supporters.

He positioned two-thirds of his force on a hill in sight of Thierry's army and held the remainder in reserve, hidden on the reverse slope.

[3] Lille had come to Thierry's side in August 1127 and Saint-Omer rebelled against William Clito in February 1128 after he had appointed an unpopular castellan.

The general assembly of Ghent then rebelled over failure of William Clito to honour a promise of a court session over his violation of the liberties of the cities of Flanders.

[3] Most of the nobility remained supporters of William Clito but Iwain of Alost and Daniel of Termonde declared for Thierry, bringing a number of Flemish knights to his cause.

He afterwards moved to Axspoele, near Thielt, to lay siege to a castle belonging to a knight named Fulk, a supporter of William Clito.

[4] Galbert does not mention the exact location of this battle in his chronicle but Simon van Gent, the abbot of the abbey of Saint Bertin in Saint-Omer, mentions in his chronicle Gesta abbatum S. Bertini Sithiensium that this battle took place in the territory of Axspoele: "Post multa decem milia malorum, cum valida manu armatorum, in campo Hackespul, Willelmus et Theodericus ad prelium conveniunt, fugatoque Theoderico cum suis, Willelmo cessit victoria; sed in brevi victorie usus est leticia".

[9] Thierry's army amounted to 300 mounted men-at-arms and 1,500 infantry, though 500 of the latter may have been left to continue to siege while he faced William Clito's troops.

[2] His defeat was attributed by contemporaries to his failure to observe the rituals around inviting an enemy to enter battle at a mutually agreed time and place.

[9][1] The siege progressed well for William Clito but he suffered a minor wound to his hand that became infected and led to his death, without an heir, on 28 July 1128.