The Discrete Gaussian Chain is a model of interfaces $Ψ: \mathbf{Z} \to \mathbf{Z}$ governed by the Hamiltonian $$ H(Ψ)= \sum_{i\neq j} J_α(|i-j|) |Ψ_i -Ψ_j|^2 $$ with long-range coupling constants $J_α(k)\asymp k^{-α}$. For any $α\in [2,3)$ and at high enough temperature, we prove an invariance principle for such an $α$-Discrete Gaussian Chain towards a $H(α)$-fractional Gaussian process where the Hurst index $H$ satisfies $H=H(α)=\frac {α-2} 2$. This result goes beyond a conjecture by Fröhlich and Zegarlinski [FZ91] which conjectured fluctuations of order $n^{\tfrac 1 2 (α-2) \wedge 1}$ for the Discrete Gaussian Chain. More surprisingly, as opposed to the case of the $2D$ Discrete Gaussian $Ψ: \mathbf{Z}^2 \to \mathbf{Z}$, we prove that the integers do not affect the {\em effective temperature} of the discrete Gaussian Chain at large scales. Such an {\em invisibility of the integers} had been predicted by Slurink and Hilhorst in the special case $α_c=2$ in [SH83]. We also identify a similar invisibility of integers when a $2D$ Gaussian Free Field at high temperature is conditioned to take integer values on a dilute enough "fractal subset" of $\mathbf{Z}^2$. Our proof relies on four main ingredients: (1) A Caffareli-Silvestre extension for the discrete fractional Laplacian (which may be of independent interest) (2) A localisation of the chain in a smoother sub-domain (3) A Coulomb gas-type expansion in the spirit of Fröhlich-Spencer [FS82] (4) Controlling the amount of Dirichlet Energy supported by a $1D$ band for the Green functions of $\mathbf{Z}^2$ Bessel-type random walks Finally, we also analyse the (easier) regime $α\in(1,2) \cup (3,\infty)$ as well as the $2D$ Discrete Gaussian with long-range coupling constants (for any $α>α_c=4$).