Williams was best known for being a war correspondent. He was described as an admirable war correspondent, a daring rider as well as writer. For "The Standard", he was at the headquarters of the Armée de la Loire, a French army, during the Franco-Prussian War in 1870. He was also one of the first correspondents in Strasbourg, where the French forces were defeated. In the summer and autumn of 1877, he was a correspondent to Ahmed Muhtar Pasha who commanded the Turkish forces in Armenia during the Russo-Turkish War of 1877 and 1878. Williams remained constantly at the Turkish front, and his letters were the only continuous series that reached England. In 1878, he published this series in a revised and extended form as "The Armenian Campaign: A Diary of the Campaign on 1877, in Armenia and Koordistan", which was a large accurate record of the war, even though it was pro-Turkish. From Armenia, he followed Muhtar Pasha to European Turkey and described his defence of the lines of Constantinople against the Imperial Russian Army. Williams was with General Mikhail Skobelev at the headquarters of the Imperial Russian Army when the Treaty of San Stefano was signed in March 1878. He reported this at the Berlin Congress.