Captain Lee was placed on the personal staff of General Scott, and given supervision of important road and bridge building. In a letter to his wife, dated Rio Grande, October 11, 1846, he writes: "We have met with no resistance yet. The Mexicans who were guarding the passage retired on our approach. There has been a great whetting of knives, grinding of swords, and sharpening of bayonets ever since we reached the river." This was written while serving with General Wool in northern Mexico. He took part in the battle of Buena Vista, his first engagement, and was then summoned to Vera Cruz by Scott. That doughty old General and former commandant at West Point had all along shown a great partiality for Lee; and in the campaign which was to follow, we find him constantly writing of his young staff officer in glowing terms. One such incident is typical. Lee had undertaken alone an all-night exploration of a desolate, lava tract called the Pedregal, which had been shunned by scouts and troopers alike. It was treacherous country, difficult to traverse, and possibly infested by the enemy. General Scott writes: "I had despatched several staff officers who had, within the space of two hours, returned and reported to me that each had found it impracticable to penetrate far into the Pedregal during the dark. . . . Captain Lee, having passed over the difficult ground by daylight, found it just possible to return to San Augustin in the dark, the greatest feat of physical and moral courage performed by any individual, in my knowledge, pending the campaign." Another General, P. F. Smith, also bears tribute to this and other such feats: "I wish partially to record my admiration of the conduct of Captain Lee, of the Engineers. His reconnaissances, though pushed far beyond the bounds of prudence, were conducted with so much skill that their fruits were of the utmost value--the soundness of his judgment and personal daring being equally conspicuous." At Vera Cruz Lee had the pleasure of meeting his older brother, from whom he had long been separated. This was Lieutenant Sydney Smith Lee, who had entered the Navy before Robert went to West Point. Now for the first time the brothers, sailor and soldier, fought side by side. But it was with mixed feelings that Robert Lee passed through this experience. He was brave enough on his own account, but he constantly trembled for Sydney! He had placed a battery in position to reduce the town, and thus describes the ensuing action: "The first day this battery opened Smith served one of the guns. I had constructed the battery, and was there to direct its fire. No matter where I turned, my eyes reverted to him, and I stood by his gun whenever I was not wanted elsewhere. Oh! I felt awfully, and am at a loss what I should have done had he been cut down before me. I thank God that he was saved. He preserved his usual cheerfulness, and I could see his white teeth through all the smoke and din of the fire."