Haag was a German painter and watercolourist of landscapes, portraits and Eastern subjects. His pictures of eastern subjects brought him fame and prosperity. He was born at Erlangen, Bavaria and studied at Nuremberg and Munich. In Brussels, he worked as a miniature painter. When he came to England, in 1847, he continued to paint miniature portraits and started to work as a watercolourist. In 1854, he visited Dalmatia and Montenegro and from 1858-60 he travelled in Egypt and the Middle East, with Frederick Goodall. In 1850, Haag became an Associate of the Royal Watercolour Society. He exhibited at the British Institute, the Fine Art Society, the Grosvenor Gallery, the Walker Art Gallery Liverpool, the Manchester City Art Gallery, the Old Watercolour Society, the Royal Academy, the Royal Society of British Artists and the Royal Society of Painters in Watercolours.