At the same time, efforts were made by the British to feed false
intelligence to the Germans that an overwhelming British force was being assembled, including
Force H (the
aircraft carrier HMS Ark Royal and the
battlecruiser HMS Renown), when in fact the two 6" cruisers had only been joined by
Cumberland which had arrived at 22:00 on 14 December, after steaming 1,014
nautical miles from the Falkland Islands in 34 hours, at an average of over 90% of her full trials speed attained over much shorter distances. The older and larger
Cumberland was more powerful than
Exeter, with an additional aft turret containing two more 8" guns, but was no match on paper for
Admiral Graf Spee whose guns had significantly longer range and fired much heavier shells (660lb against 256lb). Overwhelming British forces (HMS
Renown,
Ark Royal,
Shropshire,
Dorsetshire, and
Neptune) were
en route, but would not assemble until 19 December,... For the time being, the total force comprised the undamaged
Cumberland with a full ammunition load, and the damaged
Ajax and
Achilles with depleted stocks of shells. To reinforce the propaganda effect, these ships — which were waiting just outside the
three-mile limit — were ordered to make smoke, which could be clearly seen from the Montevideo waterfront.... the Germans were entirely deceived, and expected to face a far superior force on leaving the River Plate.
Graf Spee had also used two-thirds of her 283 mm (11.1 in) ammunition and had only enough left for approximately a further 20 minutes of firing. Such a reduced ammunition stock was hardly sufficient for the ship to fight her way out of Montevideo, let alone get back to Germany, when contrasted with the previously unengaged
Cumberland's ability to fight at full capacity for about 90 minutes and pursue at equal or higher speed for at least another 2,000 nautical miles before requiring replenishment at sea.