Final answer:
Richard the Lionhearted took part in the Third Crusade, achieving a controversial treaty with Saladin that allowed Christian pilgrims into Jerusalem but kept the city under Muslim control. After securing some territories, the Christians' crusading efforts in the Holy Land waned, and the focus turned to nation-building in Europe.
Step-by-step explanation:
In response to the barons of Jerusalem and the French crusaders urging, Richard I of England, famously known as Richard the Lionhearted, partook in the Third Crusade (1189-1192) to retake Jerusalem and assist the Outremer territories.
Despite internal squabbling among crusaders and local aristocrats, they managed to secure the coastline of the Holy Land and the island of Cyprus but failed to advance further inland.
Ultimately, Richard negotiated a treaty with the Muslim leader Saladin which ensured that Jerusalem remained under Muslim control, yet granted Christian pilgrims safe and unrestricted access to the city.
This agreement was controversial and viewed as capitulation by both Muslims and Christians, but it fulfilled the immediate practical objectives of Frederick II's Holy Land aspirations without bloodshed under the Treaty of Jaffa arranged in 1219.
The Crusader States in the Holy Land faced ongoing threats, particularly after the loss of Edessa, which led to the Second Crusade. The fall of Acre in 1291 marked the end of Crusader presence in the Holy Land.
As the focus shifted away from Jerusalem in the late Middle Ages, the rhetoric of crusade remained but was employed more to serve the political aims of consolidating burgeoning nation-states back in Europe.