Pakistan, June 20 -- In the grand tapestry of international affairs, where peace prizes have long been the preserve of singular visionaries or dedicated institutions, a remarkable chapter has now been inscribed in the name of an entire nation. On Thursday, Pakistan's Prime Minister Shahbaz Sharif set his signature on the Islamabad Memorandum of Understanding, formally establishing Pakistan as the trusted mediator between the United States and Iran. In that solemn act, history itself bent its course, awarding to Pakistan a distinction rarer than any laurel bestowed by distant committees; the mantle of peacemaker among mighty powers.

When the conflict first erupted, the world beheld a blaze fed by ancient grudges and modern suspicions, thr...