Embedding of classical polar unitals in PG(2,q2)

A unital, that is, a block-design 2−(q3+1,q+1,1), is embedded in a projective plane Π of order q2 if its points and blocks are points and lines of Π. A unital embedded in PG(2,q2) is Hermitian if its points and blocks are the absolute points and non-absolute lines of a unitary polarity of PG(2,q2). A classical polar unital is a unital isomorphic, as a block-design, to a Hermitian unital. We prove that there exists only one embedding of the classical polar unital in PG(2,q2), namely the Hermitian unital.