He it was Whom Thou hast determined to be the Herald of Thy Most Great Revelation and the Announcer of Thy Most Ancient Splendor.
(Baha'u'llah, Prayers and Meditations by Baha'u'llah, p. 128)
1899 - Arrival of the Báb's remains in the Holy Land.
Assisted by another believer, Haji Shah Muhammad buried the casket beneath the floor of the inner sanctuary of the shrine of Imam-Zadih Zayd, where it lay undetected until Mirza Asadu'llah-i-Isfahani was informed of its exact location through a chart forwarded to him by Bahá'u'lláh. Instructed by Bahá'u'lláh to conceal it elsewhere, he first removed the remains to his own house in Tihran, after which they were deposited in several other localities such as the house of Husayn-'Aliy-i-Isfahani and that of Muhammad-Karim-i-'Attar, where they remained hidden until the year 1316 (1899) A.H., when, in pursuance of directions issued by 'Abdu'l-Bahá, this same Mirza Asadu'llah, together with a number of other believers, transported them by way of Isfahan, Kirmanshah, Baghdad and Damascus, to Beirut and thence by sea to 'Akká, arriving at their destination on the 19th of the month of Ramadan 1316 A.H. (January 31, 1899), fifty lunar years after the Báb's execution in Tabriz.
(Shoghi Effendi, God Passes By, p. 274)
1983 - The Universal House of Justice takes up its permanent seat.
1985 – UHJ Explains the Lesser Peace and The Most Great Peace
Bahá'u'lláh's principal mission in appearing at this time in human history is the realization of the oneness of mankind and the establishment of peace among the nations; therefore, all the forces which are focused on accomplishing these ends are influenced by His Revelation. We know, however, that peace will come in stages. First, there will come the Lesser Peace, when the unity of nations will be achieved, then gradually the Most Great Peace -- the spiritual as well as social and political unity of mankind, when the Bahá'í World Commonwealth, operating in strict accordance with the laws and ordinances of the Most Holy Book of the Bahá'í Revelation, will have been established through the efforts of the Baha’I’s.
As to the Lesser Peace, Shoghi Effendi has explained that this will initially be a political unity arrived at by decision of the governments of various nations; it will not be established by direct action of the Bahá'í community. This does not mean, however, that the Bahá'ís are standing aside and waiting for the Lesser Peace to come before they do something about the peace of mankind. Indeed, by promoting the principles of the Faith, which are indispensable to the maintenance of peace, and by fashioning the instruments of the Bahá'í Administrative Order, which we are told by the beloved Guardian is the pattern for future society, the Bahá'ís are constantly engaged in laying the groundwork for a permanent peace, the Most Great Peace being their ultimate goal.
The Lesser Peace itself will pass through stages; at the initial stage the governments will act entirely on their own without the conscious involvement of the Faith; later on, in God's good time, the Faith will have a direct influence on it in ways indicated by Shoghi Effendi in his "The Goal of a New World Order". In connection with the steps that will lead to this latter stage, the Universal House of Justice will certainly determine what has to be done, in accordance with the guidance in the Writings, such as the passage you quoted from "Tablets of Bahá'u'lláh", page 89. In the meantime, the Bahá'ís will undoubtedly continue to do all in their power to promote the establishment of peace.