julius caesar was a roman military and political leader and one of the most influential men in world history
he played a critical role in the transformation of the roman republic into the roman empire 
his conquest of gaul extended the roman world all the way to the atlantic ocean 
and he was also responsible for the first roman invasion of britain in fifty five bc
the caesar cipher is named after julius caesar who according to suetonius 
used it with a shift of three to protect messages of military significance if he had anything 
confidential to say he wrote it in cipher 
that is by so changing the order of the letters of the alphabet that
not a word could be made out if anyone wishes to decipher these and get at their meaning 
he must substitute the fourth letter of the alphabet namely d for a and so with the others
while caesars was the first recorded use of this scheme other substitution ciphers are known to have been used 
earlier julius caesars nephew augustus also used the cipher but with a shift of one