British Diplomatic Oil Crisis: Contemporary Anglo-Saxon Geopolitical Rivalries in the Persian Gulf: Drawing a Lesson? Or Sir Anthony Eden‘s Delusion of Grandeur.

whereby
Russia acquired further territory and imposed a heavy
indemnity on Persia. Even more significant were the Commercial
privileges which Persia was forced to concede, privileges which
conferred extra-territorial rights on Russian subjects.9

Persian diplomacy with Britain
to gain an ally in the conflicts with
Russia, and the disastrous Turkmanchai Treaty of 1828 forced on
Persia, finally impressed upon Persia the danger of her position as
between Britain and Russia. The peace treaty of Turkmanchai signed
with Russia in 1828 marked the beginning of a new era. From that
time Persia ceased to be a completely independent power upon which
Britain had been counting. For the capitulating regime it was the
start of the period when Britain could directly exert pressure on
Persia to protect her interests against Russia. Britain, before the
peace treaty of 1828 between Persia and Russia, believed that the
Persian empire was declining anyhow, therefore she had already
started to make diplomatic manoeuvring in order to establish
influence in Persia’s affairs. When in 1826 Teheran applied to the
British Government for assistance, the British turned the request
down on the plea that Persia waged an aggressive war. After the 1828
Treaty of Turkmanchai between Persia and Russia, Britain exploited
Persia’s financial difficulties in order to negotiate an amendment
to the key clauses of the Definitive Treaty of 1814 which she had
signed with Persia. Later on, when Teheran tried to recover Herat
from its Afghan ruler, in order to make good the losses she had
suffered in the Caspian region, the British Government intervened
decisively, because if Persia had been successful, Russian influence
would have penetrated to the south of the Hindukush and presented a
standing