  Let $\Sigma$ a closed $n$-dimensional manifold, $\mathcal{N} \subset
\mathbb{R}^M$ be a closed manifold, and $u \in W^{s,\frac
ns}(\Sigma,\mathcal{N})$ for $s\in(0,1)$. We extend the monumental work of
Sacks and Uhlenbeck by proving that if $\pi_n(\mathcal{N})=\{0\}$ then there
exists a minimizing $W^{s,\frac ns}$-harmonic map homotopic to $u$. If
$\pi_n(\mathcal{N})\neq \{0\}$, then we prove that there exists a
$W^{s,\frac{n}{s}}$-harmonic map from $\mathbb{S}^n$ to $\mathcal{N}$ in a
generating set of $\pi_{n}(\mathcal{N})$.
  Since several techniques, especially Pohozaev-type arguments, are unknown in
the fractional framework (in particular when $\frac{n}{s} \neq 2$ one cannot
argue via an extension method), we develop crucial new tools that are
interesting on their own: such as a removability result for point-singularities
and a balanced energy estimate for non-scaling invariant energies. Moreover, we
prove the regularity theory for minimizing $W^{s,\frac{n}{s}}$-maps into
manifolds.
