Rawlinson remained at home for two years, published in 1851 his memoir on the Behistun inscription, and was promoted to the rank of lieutenant-colonel. He disposed of his valuable collection of Babylonian, Sabaean, and Sassanian antiquities to the trustees of the British Museum, who also made him a considerable grant to enable him to carry on the Assyrian and Babylonian excavations initiated by Layard. During 1851 he returned to Baghdad. The excavations were performed by his direction with valuable results, among the most important being the discovery of material that contributed greatly to the final decipherment and interpretation of the cuneiform character. Rawlinson's greatest contribution to the deciphering of the cuneiform scripts was the discovery that individual signs had multiple readings depending on their context. While at the British Museum, Rawlinson worked with the younger George Smith.