The Unknown Capablanca (David Hooper & Dale Brandreth, Batsford, 1975, p.108):

"For some time before the tournament at Hamburg in 1910 F. J. Marshall analysed a new move for White in the Max Lange (15.Bh6). He successfully sprang this on Tarrasch (Marshall vs Tarrasch, 1910), who had made a characteristic pronouncement to the effect that the Max Lange favoured Black.

"Afterwards a match of six games was arranged to test the value of Marshall's new move. Capablanca was to take the Black pieces in every game. Play was to take place daily, commencing on the 3rd of October 1910. It is not clear whether this happened; for the last game was apparently played some weeks later. The result of this handicap match is also not clear; it may have been, from White's point of view, 3+ 2- 1=."

The (New York) Sun, October 16th, 1910, reports the match in progress, with the score 2-1 to Marshall after three games, Capablanca having won the first.

American Chess Bulletin, November 1910, p.262, also has Marshall leading 2-1 with no draws.

Jose Raul Capablanca - A Chess Biography (Miguel Sanchez, McFarland, 2015, p.131):

"Capablanca played from October 3 to November 15 a very little-known match of six games against Marshall, with a forced line of the Max Lange attack ... The match was sponsored by Professor Rice ... but was not exactly a theoretical dispute as was the Steinitz-Chigorin cable match of 1891. This was another indication that Capablanca found a good reception among chess patrons, who paid him for exhibitions of this kind or for private meetings, although he always provided very little information about such affairs."

The three surviving game scores we owe to the 1913 publication by Marshall of <Modern Analysis of the Chess Openings>. See C.N. 11529.