The Hansa-Brandenburg W.29 was a German monoplane fighter floatplane which served in the closing months of World War I, from bases on the North Sea coast.

 It was based on the W.12 biplane that it was designed to replace. The monoplane configuration created less drag, and thus gave greater speed.

Friedrich Christiansen was a German ace during WW1. In August 1914, Christiansen was called up and posted to Zeebrugge as naval aviator. He flew Hansa-Brandenburg W.12 seaplanes over the North Sea, the English Channel, and Britain. For his bombing missions on Dover and Ramsgate, he was awarded the Iron Cross 2nd Class. From 1915 to 1916 Christiansen went on numerous reconnaissance and bombing missions, helping to make his unit at Zeebrugge one of the most successful in the German Naval Air Service. On 27 April 1916, as Leutnant der Matrosen Artillerie (Lieutenant of Naval Artillery,) Christiansen was awarded the Iron Cross 1st Class and Knights Cross with Swords of the House Order of Hohenzollern.

Christiansen claimed his first air-to-air victory 15 May 1917 by shooting down a Sopwith Pup off Dover. On 1 September 1917 he took command of Naval Air Station at Zeebrugge, and being promoted to Oberleutnant zur See, shot down a Porte FB2 Baby off Felixstowe the same day. On 11 December 1917 he shot down the non-rigid coastal class airship C-27, Cdr. Flight Lieutenant John Francis Dixon, DSC, near the Belgian coast.

Christiansen continued to carry out reconnaissance, rescue, and bombing missions, such that by December 1917, he had completed 440 missions, including shooting down Airship C27. At this time he was also awarded the Pour le Mérite ("Blue Max"), the first of only three given to naval aviators and the only one to a seaplane pilot. He was promoted to Kapitänleutnant in 1918.

On 15 February 1918 Christiansen shot down a Curtiss H12B flying boat off Felixstowe, followed by 2 more on 24 April and 25 April. In June he claimed three more Felixstowe F2As. On 6 July he surprised and damaged British submarine HMS C25 in the Thames estuary, killing its captain and five crewmen (the submarine reached harbour). By 11 November 1918 he raised his personal tally to 13, as well as some shared victories, which cumulatively may have brought his total to 21.