Simplify the following text for a Grade 11 native English-speaking person.
Original: '' ... Stratagem was , therefore , indispensable ; and it was necessary to blind Varus to their schemes until a favorable opportunity should arrive for striking a decisive blow ... '' British historian Edward Shepherd Creasy ( 1812 -- 1878 )
Simplified: '' ... Stratagem was , therefore , indispensable ; and it was necessary to blind Varus to their schemes until a favorable opportunity should arrive for striking a decisive blow ... '' , British historian Edward Shepherd Creasy ( 1812-1878 )