Final answer:
Conrad, as the titular king of Jerusalem, refused to rebuild the city’s defensive walls due to the stipulations of the Treaty of Jaffa, which also prohibited expelling Muslims or confiscating their wealth and ensured Muslim control over their holy sites.
Step-by-step explanation:
Conrad, despite being the titular king of Jerusalem, refused to rebuild the city’s walls. The Treaty of Jaffa, which was negotiated by Hohenstaufen ruler Frederick II, placed Conrad as the ruler, but with limited power, and the treaty carried several restrictions. Muslims could practice Islam, their holy sites remained under Muslim control, and the treaty included a clause prohibiting the reconstruction of Jerusalem's city walls, which left the city defenseless.
The agreement was seen as a capitulation and caused mistrust among Christians towards Frederick, as it was acquired through negotiation rather than battle. Furthermore, the stipulation against the rebuilding of Jerusalem’s defensive walls was a significant point of tension, as it left the city vulnerable to potential attacks. Conrad's refusal to rebuild the walls was likely influenced by the conditions set forth in the agreement and the delicate balance of power between the Christians and Muslims in the region.