  The phenomenon of the deconfinement -- the spectacular drop of the
colorelectric string tension at the critical temperature $T_c$ -- is studied
within the method of field correlators (FCM) taking into account directly the
contribution of the gluon condensate into the hadronic free energy. Using the
resulting expressions for the free energy as a sum of the gluon condensate (the
vacuum energy) and the hadronic pressure one obtains the possibility to
calculate the deconfinement temperature $T_c$ and the temperature behavior of
the string tension $\sigma_E(T)$ and the gluonic condensate $G_2(T)$ below
$T_c$. The connection between the string tension and the quark condensate found
in the framework of FCM allows the predict also the latter as a function of $T$
. These results are compared to the known lattice data of $T_c$, $\sigma_E(T)$,
$\langle \bar{q}q \rangle(T)$ for hadronic media with different $n_f$ and $m_q$
and in the external magnetic field $eB$. The good agreement of the results of
this approach with lattice data is demonstrated.
