How was cuneiform deciphered throughout history?

Cuneiform script is the earliest known writing system in the world. Knowledge of cuneiform was lost until AD 1835, when Henry Rawlinson, an English army officer, found some inscriptions on a cliff at Behistun in Persia. Carved in the reign of King Darius of Persia they consisted of identical texts in three languages: Old Persian, Babylonian and Elamite. After translating the Persian, Rawlinson began to decipher the others. By 1851 he could read 200 Babylonian signs.

Before Rawlinson, scholars tried to figure out what the Words on ancient clay tablets meant, but they had no guidelines. Georg Grotefund, a high school teacher in Germany, was sure the cuneiform wedges represented some type of alphabet. Using two different inscriptions from a gate at Persepolis Grotefund isolated what he believed were royal names. He was right, but he couldn't really do more without a kind of Rosetta Stone for cuneiform.

The Rosetta Stone (with its three inscriptions in hieroglyphs, demotic Egyptian and Greek which all say the same thing) was rediscovered in Rashid (Rosetta), Egypt in 1799 by Napoleon's army. Because a young French Egyptologist, Jean Francois Champollion, could work with two of the three languages, he was able to unlock the secret to the third language: Egyptian hieroglyphics.